United States

I will provide an overview on our work to experimentally quantify and verify the presence of spin-mixed states in ferromagnetic 3d transition metals via the precise
measurement of the orbital moment. [1] While central to phenomena such as Elliot-Yafet scattering, quantification of the spin-mixing parameter &lt;&#39;b&#39;&lt;sup&gt;2&lt;/sup&gt;&gt; has hitherto been confined to
theoretical calculations. We demonstrate that this information is also available by experimental means. Comparison of ferromagnetic resonance (FMR) spectroscopy with x-ray magnetic
circular dichroism (XMCD) results show that Kittel’s original derivation [2] of the spectroscopic g-factor requires modification, to include second order terms in spin-mixing of valence
band states. Such modification can have a large effect on the measured value of the spectroscopic g-factor in these materials. Not only does it explain discrepancies between XMCD and
FMR, but provides the means to quantify &lt;&#39;b&#39;&lt;sup&gt;2&lt;/sup&gt;&gt;. Our results are supported by ab-initio relativistic electronic structure theory, which show good agreement between the measured and predicted values of &lt;&#39;b&#39;&lt;sup&gt;2&lt;/sup&gt;&gt;.&lt;br&gt;
**References** &lt;br&gt;
[1] J. M. Shaw, R. Knut, A. Armstrong, S. Bhandary, Y. Kvashnin, D. Thonig, E. K. Delczeg-Czirjak, O. Karis, T. J. Silva, E. Weschke, H. T. Nembach, O. Eriksson, and D.
A. Arena, Phys. Rev. Lett. 127, 207201 (2021).
[2] C. Kittel, Phys. Rev. 76, 743 (1949). &lt;br&gt;

![](https://s3.eu-west-1.amazonaws.com/underline.prod/uploads/markdown_image/1/image/c78e22817d83e5b27034d803930513ce.png)&lt;br&gt;
Figure 1: Experimental values of &#39;/s obtained from XMCD and FMR for a 10 nm thick Ni&lt;sub&gt;80&lt;/sub&gt;Fe&lt;sub&gt;20&lt;/sub&gt;
sample. The value obtained from XMCD is indicated as the horizontal dashed line. In the
case of FMR (solid line), µ&lt;sub&gt;L&lt;/sub&gt; / µ&lt;sub&gt;S&lt;/sub&gt; is calculated from the experimentally determined g-factor and application of the modified equation for the g-factor for various values of b&lt;sup&gt;2&lt;/sup&gt;. The value of b&lt;sup&gt;2&lt;/sup&gt;= 0.02 for this material can be graphically determined by the intersection of the two lines.&lt;br&gt;

MMM 2022

Quantifying Spin Mixed States in Ferromagnets

I will provide an overview on our work to experimentally quantify and verify the presence of spin-mixed states in ferromagnetic 3d transition metals via the precise
measurement of the orbital moment. [1] While central to phenomena such as Elliot-Yafet scattering, quantification of the spin-mixing parameter <'b'2> has hitherto been confined to
theoretical calculations. We demonstrate that this information is also available by experimental means. Comparison of ferromagnetic resonance (FMR) spectroscopy with x-ray magnetic
circular dichroism (XMCD) results show that Kittel’s original derivation [2] of the spectroscopic g-factor requires modification, to include second order terms in spin-mixing of valence
band states. Such modification can have a large effect on the measured value of the spectroscopic g-factor in these materials. Not only does it explain discrepancies between XMCD and
FMR, but provides the means to quantify <'b'2>. Our results are supported by ab-initio relativistic electronic structure theory, which show good agreement between the measured and predicted values of <'b'2>. 
**References** 
[1] J. M. Shaw, R. Knut, A. Armstrong, S. Bhandary, Y. Kvashnin, D. Thonig, E. K. Delczeg-Czirjak, O. Karis, T. J. Silva, E. Weschke, H. T. Nembach, O. Eriksson, and D.
A. Arena, Phys. Rev. Lett. 127, 207201 (2021).
[2] C. Kittel, Phys. Rev. 76, 743 (1949). 

![](https://s3.eu-west-1.amazonaws.com/underline.prod/uploads/markdown_image/1/image/c78e22817d83e5b27034d803930513ce.png) 
Figure 1: Experimental values of '/s obtained from XMCD and FMR for a 10 nm thick Ni80Fe20
sample. The value obtained from XMCD is indicated as the horizontal dashed line. In the
case of FMR (solid line), µL / µS is calculated from the experimentally determined g-factor and application of the modified equation for the g-factor for various values of b2. The value of b2= 0.02 for this material can be graphically determined by the intersection of the two lines.

technical paper

#### Welcome to the 67th Annual Conference on Magnetism and Magnetic Materials, MMM 2022!

The Conference was held from October 31 to November 4 and offers both in-person and on-demand content.

MMM 2022 is sponsored jointly by AIP Publishing and the IEEE Magnetics Society. Members of the international scientific and engineering communities interested in recent developments in fundamental and applied magnetism are invited to attend and contribute to the technical sessions. The technical program will include invited and contributed papers in oral and poster sessions, invited symposia, a tutorial, and several special sessions. This Conference provides an outstanding opportunity for worldwide participants to meet their colleagues and collaborators and discuss developments in all areas of magnetism research.

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Manganites are one of the promising materials due to their great diversity in physical properties [1-4]. These properties can be tuned by varying probability occupancy as well as ionic size of A-site cations, such as long range ordering observed in RBaMn2O6 (R=Rare earth ions) can be suppressed by cationic disorder [5-6]. We made a comparative study of structure, magnetic (M) properties and magneto-resistance (MR) in A-site ordered NdBaMn2O6 (O-NB) and A-site disordered NdBaMn2O6 (D-NB), NdCaMn2O6 (D-NC). Experimental results from T dependent synchrotron PXRD (fig.1.a-c) concluded that structural symmetry strongly depends on A-site cationic distribution and their ionic sizes resulting in intriguing magnetic ground states. Moreover, MR (fig.2) is considerably large in disordered systems as compared to ordered one. Refinement of PXRD data showed that the A-site cations (Nd3+ & Ba2+) are completely ordered in O-NB. Lowering the T is accompanied with structural transition (ST) (fig.1.a) to lower space group. Whereas, there is no ST in disorder system, D-NB down to 120K. However, ST has been restored again in D-NC disordered system due to similar A-site cationic sizes, Nd3+ and Ca2+ ions. At the same time, M-T data show AFM ground state due to lower structural symmetry in O-NB and the ground state becomes FM in case of D-NB system due to the retainment of higher symmetric structure upto lowest T. Interestingly, AFM state has been restored in D-NC similar to that of O-NB due to presence of cationic disorder of similar sizes (fig.1.d-f). So, it can be argued that crystal structure and magnetic degrees of freedoms are strongly correlated with each other. Further, MR studies depict 3 times higher value of MR in both disorder compounds to that of order one (fig.2). However, behaviour of MR with H is different for D-NB and D-NC implying a different origin of this large MR in these compounds. We believe that the presence of phase separation in D-NC and AFM fluctuation in D-NB might be possible origin of their large MR with respect to O-NB system. 
**References** 
[1] V.N. Smolyaninova, S.E. Lofland, C. Hill , R.C. Budhani, Z. Serpil Gonen, B.W. Eichhorn, and R.L. Green, Effect of A-site cation disorder on charge ordering and ferromagnetism of La0.5Ca0.5-yBayMnO3, J. Magn. Magn. Mater.248 (2002) 348. 
[2] T. Nakajima, H. Kageyama, H. Yoshizawa, K. Ohoyama, and Y. Ueda, Ground State Properties of the A-site Ordered Manganites, RBaMn2O6 (R = La, Pr and Nd), J. Phys. Soc. Jpn. 72 (2003) 3237. 
[3] J. Blasco, G. Subías, M. L. Sanjuán, J. L. García-Muñoz, F. Fauth, and J. García, Structure and phase transitions in A-site ordered RBaMn2O6 (R=Pr,Nd) perovskites with a polar ground state, Phys. Rev. B 103 (2021), 064105. 
[4] S. Yamada, H. Sagayama, K. Higuchi, T. Sasaki, K. Sugimoto, and T. Arima, Physical properties and crystal structure analysis of double-perovskite NdBaMn2O6 by using single crystals, Phys. Rev. B 95 (2017) 035101. 
[5] D. Akahoshi, M. Uchida, Y. Tomioka, T. Arima, Y. Matsui, and Y. Tokura, Random Potential Effect near the Bicritical Region in Perovskite Manganites as Revealed by Comparison with the Ordered Perovskite Analogs, Phys. Rev. Lett. 90 (2003) 177203. 
[6] T. Nakajima, H. Yoshizawa, and Y. Ueda, A-site Randomness Effect on Structural and Physical Properties of Ba-based Perovskite Manganites, J. Phys. Soc. Jpn. 73 (2004) 2283. 

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Role of Cationic Size Mismatch to Control the Effect of A site Disorder

Chromium-rich Cr-V alloys exhibit three phases: Paramagnetic phase (P) above NÃ©el temperature (TN), a transverse polarization spin-density-wave (SDW) phase (AF1) below TN and above the spin-flip temperature (TSF), and a longitudinal polarization SDW phase (AF2) below TSF. Varying the electron/atom ratio in the Cr alloy, one can go from incommensurate to commensurate SDW and modifies different physical properties [1]. In the paramagnetic phase, Cr exhibit a Pauli susceptibility with slight temperature dependence[1]. Otherwise, the introduction of small amounts of V in Cr not only changes TN, but also induced a Curie-Weiss behavior (CW) that we have associated to local magnetic moments. This behavior is limited up to 0.7%V and magnetic fields of 15 kOe [2]. This behavior was also observed for different Cr alloys [3-5]. The origin of local magnetic moments has been associated with the establishment of local spin-density waves (LSDW) around V impurities [2,6]. In this work, we presented an investigation of the effects of local magnetic moments in antiferromagnetic phases in Cr-V alloys. The samples are single crystals with a concentration up to 0.7% V. Magnetization measurements as a function of temperature were performed using a VSM SQUID magnetometer MPMS3 by Quantum Design using zero field cooling (ZFC) and field cooling (FC) protocols. Figure 1 presents the magnetic susceptibility (Ï‡DC(T)) as a function of temperature under a magnetic field H = 100 Oe (a) and 10 kOe (b) for single crystal of Cr-0.4 at.%V. The ZFC measurement shown in Fig 1(a) shows a jump as TN is approached followed by a C-W behavior up to 400 K. However, below TN Ï‡DC (T) the FC measurement exhibit a strong anisotropy, likely associated with local magnetic moments frozen in the cooling process, from the paramagnetic phase. Fig 1(b) shows that 10 kOe suppresses the CW effect above TN, in the AF1 phase Ï‡DC is identical for both processes ZFC and FC and in the AF2 phase Ï‡DC becomes larger for ZFC as compared to FC. These results show that local moments around V impurities depend on magnetic history.

Magnetic Anisotropy as an Evidence of Local Magnetic Moments in Paramagnetic Phase of Cr V Alloys

Two-dimensional van der Waals (vdW) heterostructures are at the forefront of research due to their extensive potential as a platform for spintronics and opto-spintronics applications [1]. Room-temperature ferromagnetism has been achieved in several two-dimensional (2D) magnetic materials and heterostructures [2,3]. Ferromagnetic 2D semiconductors are of particular interest since they allow for simple integration with current silicon-based electronics and their properties can be easily tuned with electric fields and optical excitations. Recently, we demonstrated light tunable magnetism in V-doped WS2 (V-WS2) monolayers, mediated by optically injected charge carriers [4]. A similar effect was shown in ML-VSe2/BL-MoS2 heterostructures in which the magnetization of VSe2 penetrates into the non-magnetic optically active MoS2 layer, allowing for the tunability of the magnetic properties of the heterostructure with light. The VSe2 layer facilitates charge separation, which promotes changes in the magnetization of the MoS2 layer, showing an enhanced light mediated magnetism effect compared to V-WS2. We present a study of related 2D magnetic heterostructures where we compare the magneto-optical response of VSe2/MoS2, VSe2/WS2 and V-MoS2/graphene heterostructures. We propose that, as the VSe2 layer in the VSe2/MoS2 heterostructure allows for charge separation through the interface, graphene in a V-MoS2/graphene heterostructure may play a similar role. The difference between the two systems lies in the source of the magnetism of the semiconducting layer. In the VSe2/MoS2 and VSe2/WS2 systems, the ferromagnetic VSe2 layer is responsible for the proximity magnetism in the non-magnetic MoS2 layer, while in V-MoS2/graphene the semiconducting layer is magnetically doped. Moreover, V-MoS2 shows enhanced magnetic properties when interfaced with graphene, compared to samples grown on Si/SiO2 which may further influence the interaction between the optically injected charge carriers and the magnetic dopants. These findings show how the interactions between photogenerated charge carriers and 2D magnetic semiconductors can be tuned in carefully constructed vdW heterostructures. 
**References** [1] J.F. Sierra, J. Fabian, and R.K. Kawakami, Nature Nanotechnology., Vol. 16, p. 856-868 (2021)
[2] F. Zhang, A. Sebastian, D.H. Olson, Advanced Science., Vol. 7, p. 2001174 (2020)
[3] M. Bonilla, S. Kolekar, Y. Ma, Nature Nanotechnology., Vol.13, p. 289-293 (2018)
[4] V. Ortiz Jiménez, Y.T.H. Pham, M. Liu, Advanced Electronic Materials., Vol. 7, p. 21000310 (2021)

Light mediated magnetism in van der Waals magnetic heterostructures

Antiferromagnets (AFMs) are strong candidates for future spintronic applications largely because of their fast dynamics and lack of stray fields. For the required switching of the Néel vector (staggered magnetization), the predicted current-induced bulk Néel spin-orbit torque (NSOT) (1) is most promising. Only two compounds with the required symmetry are known: for both CuMnAs (2,3) and Mn2Au (4,5) experimental evidence for current-induced NSOT was shown based on a small modification of the AFM domain pattern. However, the significance of NSOT for current-induced manipulation of Neel vector orientation stays controversial because competing heating-related mechanisms result in similar effects (6-8).
Here, we investigate the effect of current pulsing with different lengths along the different crystallographic directions on the AFM domain pattern of epitaxial Mn2Au (001) thin films. In-situ imaging of AFM domains before and after the current pulses was performed using x-ray magnetic linear dichroism photoemission electron microscopy (XMLD-PEEM). Reversible and repeated 90° Neel vector rotation of essentially the complete active area of the pattern cross structures was observed (Fig. 1).
Switching was only observed for current parallel to the easy crystallographic axis resulting in a Néel vector rotation perpendicular to the pulse direction, which is consistent with the NSOT. The required current density for switching is essentially independent of the pulse length (10 µs to 1 ms) indicating that thermal activation or other thermal effects are not significant. For current pulses applied parallel to a <100> hard axis, inversion of the current pulse polarity led to a partially reversible motion of domain walls, which is consistent with the NSOT acting on them. Our results confirm the fundamental role of NSOT for current-induced Néel vector switching in Mn2Au, providing an effective mechanism for spintronics applications. 

**References:** 
(1) J. Zelezný H. Gao, K. Výborný et al., Phys. Rev. Lett. 113, 157201 (2014). 
(2) P. Wadley, B. Howells, J. Zelezný et al., Science 351, 587 (2016). 
(3) P. Wadley, S. Reimers, M. J. Grzybowski et al., Nat. Nanotechnol. 13, 632 (2018). 
(4) S. Bodnar L. Smejkal, I. Turek et al., Nat. Commun. 9, 348 (2018). 
(5) S. Y. Bodnar, M. Filianina, S. P. Bommanaboyena et al., Phys. Rev. B 99, 140409(R) (2019). 
(6) T. Matalla-Wagner, J.-M. Schmalhorst, G. Reiss et al., Phys. Rev. Res. 2, 033077 (2020). 
(7) H. Meer, O. Gomonay, C. Schmitt et al., arXiv:2205.02983v1 [cond-mat.mtrl-sci]. 
(8) H. Meer, F. Schreiber, C. Schmitt et al., Nano Lett.21, 114-119 (2020). 

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Néel spin orbit torque induced remnant switching of the Néel vector in antiferromagnetic Mn2Au

Recently, two-dimensional (2D) materials have emerged as a replacement for heavy metals (HM) because of their large spin-charge interconversion efficiency [1]. In this work, we explore a promising and relatively less explored 2D monochalcogenide SnS for spintronics application. Through symmetry arguments, it is proposed that SnS should exhibit unconventional spin-orbit torques (SOTs), which is very important for energy-efficient switching of magnets with perpendicular magnetic anisotropy (PMA) [1]. SnS thin films up to monolayer (ML) thickness have been grown on Si/SiO2 substrates using pulsed laser deposition (PLD) technique at 200 °C and room temperature (RT). Two typical Raman active modes (Ag and B3g) [2] can be distinguished in the acquired Raman spectra [Fig. 1]. We performed spin-torque ferromagnetic resonance (STFMR) measurements to investigate the SOTs in SnS/Ni80Fe20 system. For ST-FMR measurements, we fabricated SnS/Ni80Fe20 rectangular microstrips using the lift-off technique. For STFMR measurements, an in-plane RF current of frequency varying from 4 GHz to 8 GHz was applied to the bilayer in the presence of an external magnetic field (H). We measured the voltage (Vmix) across the device, which originated due to the mixing of AMR and RF current. We determine the in-plane and out-of-plane torque components by fitting the Vmix with a sum of symmetric and antisymmetric Lorentzian. We performed a complete angular dependence of the STFMR signal by varying the magnetization angle φ in the sample plane. In addition to a conventional sin2φcosφ (Vy,s) dependence, we found sin2φ (Vz,s) dependence [Fig. 2], which is a signature of unconventional out-of-plane anti-damping like torque [3]. Thus our results suggest that SnS can be used to achieve efficient switching of magnetic devices with PMA via the strong unconventional out-of-plane anti-damping like torque. 
**References** [1] Y. Liu et. al., ACS Nano 14, 9389 (2020).
[2] A.N. Mehta et. al., J. Microsc. 268, 276 (2017).
[3] D. MacNeill, et al., Nat. Phys. 13, 300 (2017). 

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Evidence of unconventional spin orbit torque in SnS/Ni80Fe20 heterostructures

Spin-wave band structures can be engineered by varying the crystal geometries and this is important to facilitate the realization of many functional magnonic devices [1],
such as band stop filters and magnonic transistors. Recently, we have shown [2] the magnetostatic mode formation in an artificial magnetic structure, going beyond the crystal geometry to
a fractal structure, where the mode formation is related to the geometric scaling of the fractal structure. Fractals [3] are composed of self-similar structures across different length scales,
which look similar under different magnifications. This property is commonly referred to as dilation symmetry. Snowflakes, Romanesco broccoli, and coastlines are popular examples of
fractals observed in nature. We have determined the evolution of the magnetostatic spin-wave modes from a simple geometric structure toward a Sierpinski carpet and Sierpinski triangle by imaging the precessional
dynamics using time resolved scanning Kerr microscope as shown in Fig. 1. The experimentally observed evolution of the precessional motion could be linked to the progression in the
geometric structures that results in a modification of the demagnetizing field. Furthermore, we have found sets of modes at the ferromagnetic resonance frequency that form a scaled spatial
distribution following the geometric scaling. Based on this, we have determined the two conditions for such mode formation to occur. One condition is that the associated magnetic
boundaries must scale accordingly, and the other condition is that the region where the mode occurs must not coincide with the regions for the edge modes. This established relationship
between the fractal geometry and the mode formation in magnetic fractals provides guiding principles for their use in magnonics applications. 
**References:** M. Krawczyk and D. Grundler, J. Phys.: Condens. Matter 26, 123202 (2014).
J. Zhou, M. Zelent, Z. Luo, V. Scagnoli, M. Krawczyk, L. J. Heyderman, S. Saha, Phys. Rev. B 105, 174415 (2022)
C. Swoboda, M. Martens, and G. Meier, Phys. Rev. B 91, 064416 (2015). 

![](https://s3.eu-west-1.amazonaws.com/underline.prod/uploads/markdown_image/1/image/24a9a1dd46c44dd22e7bdb62c2ca9011.png) 
Fig. 1: SEM and scanning Kerr images of (a) Sierpinski triangles (b) Sierpinski squares with iteration number 3.

Precessional dynamics of geometrically scaled magnetostatic spin waves in two dimensional magnonic fractals

Accurate calculation of the hysteresis characteristics of magnetic materials is of great significance for the optimal design of electrical equipment. In previous studies, the Preisach model based on the centered cycle method is widely used for the simulation of hysteresis characteristics as this method uses data that can be easily obtained [1]. However, the existing centered cycle method model cannot correctly consider the influence of reversible magnetization and leads to a large error when calculating the small major hysteresis loops [2]. In this paper, an improved centered cycle method for identifying the Preisach distribution function (PDF) considering the reversible magnetization is proposed, which can improve the accuracy of predicting the symmetrical minor loops. II Method and Discussion As shown in Figure 1, an improved PDF identification method considering the reversible magnetization is proposed, which is consistent with the principle of the magnetization process. The reversible relative permeability is obtained by derivation at the reversal points of the centered cycles with different measured magnetic flux densities and obtained parametric equation, which is integrated to obtain the reversible magnetization. Four centered cycles of different magnetic flux densities are used to discretize the Preisach plane, and the values of the PDF are calculated through the modified magnetic flux densities. The irreversible magnetization is obtained by accumulating the values of the PDF. The final output value is obtained by superposing the irreversible magnetization and the reversible magnetization. The simulation results of grain-oriented silicon steel based on B30P105 are shown in Fig. 2, and the expected accuracy can be achieved. III Conclusion In this paper, a modified Preisach model with centered cycle method under the magnetization principle is developed. Obtained results show that the accuracy of the simulated symmetrical minor loops can be improved. 

**References** 
[1] Bernard Y, Mendes E, Ren Z. Determination of the distribution function of Preisach’s model using centred cycles[J]. COMPEL: The International Journal for Computation
and Mathematics in Electrical and Electronic Engineering, 2000.
[2] Peng D, Sima W, Ming Y, et al. An Improved Centered Cycle Method for Identifying the Preisach Distribution Function[J]. IEEE Transactions on Magnetics, 2018, PP(11):1-5. 

![](https://s3.eu-west-1.amazonaws.com/underline.prod/uploads/markdown_image/1/image/8452cc04d3ef3c8756ca45abe73b8393.png) 

Fig.1. (a) Discretized Preisach Plane.
(b) Numerical discrete calculation process of improved Preisach Model. 

![](https://s3.eu-west-1.amazonaws.com/underline.prod/uploads/markdown_image/1/image/cece0b04c75fbf57da22b132e9edf631.png) 

Fig.2. Comparison of simulation results of B30P105 silicon steel.
(a) Bp=0.2T. (b) Bp=0.5T. (c) Bp=0.7T. (d) Bp=1.1T.

An improved Preisach distribution function identification method considering reversible magnetization effect

Recently, multifunctional composite materials with magnetic wire inclusions for non-destructive and non-contact stress and temperature monitoring have been proposed [1]. Therefore, studies of temperature dependence of the Giant magnetoimpedance, GMI, effect become essentially relevant. There are only very few studies on temperature dependence of GMI and most of them were performed in thick amorphous wires without glass coating and in very limited temperature range [2,3,4]. Although usually the highest GMI effect is observed in Co-rich magnetic wires, GMI effect of Fe-rich glass-coated microwires can be substantially improved by stress-annealing induced magnetic anisotropy [5]. 
GMI effect and magnetic properties under temperature influence of as-prepared and stress annealed (annealing temperature Tann= 325 oC, stress applied during the annealing σ= 190MPa) thin amorphous Fe75B9Si12C4 glass-coated microwires produced by the Taylor Ulitovsky technique are analyzed. Remarkable change in the hysteresis loops and GMI effect is observed for both samples upon heating. For as-prepared FeBSiC microwire a beneficial influence of temperature on the GMI ratio is observed and hysteresis loops change of character from almost rectangular shape to inclined one (Fig.1). On the other hand, although GMI ratio improvement after stress-annealing decreases with the temperature increasing (Fig.2), temperature dependence can be tuned by the stress annealing conditions. Additionally, almost complete reversibility of the changes induced by the temperature is observed. 
Temperature dependence of the hysteresis loops and GMI effect of studied microwires is explained considering the heating effect on the internal stresses relaxation, the modification of the thermal expansion coefficients of the metallic nucleus and the glass coating and in terms of the Hopkinson effect. 
**References:** [1] A. Allue et al., Compos. Part A Appl. Sci. and Manuf., Vol. 120, p.12 (2019). 
[2] J. Nabias, A. Asfour and J. Yonnet, IEEE Trans. Magn., Vol. 53(4), p.4001005 (2017). 
[3] J.D. Santos, R. Varga, B. Hernando and A. Zhukov, J. Magn. Magn. Mater. 321, p.3875 (2009). 
[4] M. Kurniawan et al., J. Electron. Mater., Vol. 43, p.4576 (2014). 
[5] V. Zhukova et al., Scr. Mater., Vol. 142, p.10 (2018). 

![](https://s3.eu-west-1.amazonaws.com/underline.prod/uploads/markdown_image/1/image/4bac301404213f54c4bb4adca5d0984b.png) 
Fig.1. Hysteresis loops (a) and GMI ratio at f= 50 MHz (b) of as-prepared sample, measured at different temperature. 
![](https://s3.eu-west-1.amazonaws.com/underline.prod/uploads/markdown_image/1/image/2cf9acf5640bce6a1403026372c49c55.png) 
Fig.2. Hysteresis loops (a) and GMI ratio at f= 50 MHz (b) of stress annealed sample at 325 oC during 15 min (applied stress σ= 190 MPa), measured at different temperature.

Effect of temperature on magnetic properties and magnetoimpedance effect in Fe rich microwires

Magnetic multilayers constitute a rich class of material systems with a number of precisely tunable parameters (e.g., layer thickness and repeat number) that determine both their magnetic and electronic properties [1]. We present a comprehensive characterization of structural and magnetic properties of the novel system Pt/Co/Mn, which extends the group of Pt/Co/X (X = metal) multilayers that have been investigated thus far. The structural properties of the sputter-deposited Pt/Co/Mn stacks were determined from X-ray reflectometry and scanning transmission electron microscopy experiments. Subsequently, we performed magnetometry measurements in order to study hysteresis loops as a function of varying layer thickness values. We demonstrate that an increasing Co layer thickness changes the magnetic anisotropy from out of plane to in plane, whereas the deposition of thicker Mn layers leads to a decrease in the saturation magnetization, see Fig. 1. Temperature-dependent magnetometry measurements reinforce the hypothesis of antiferromagnetic coupling at the Co/Mn interfaces being responsible for the observed Mn thickness dependence of the magnetization reversal. Moreover, magneto-optical imaging experiments indicate systematic changes in magnetic domain patterns as a function of the Co and Mn layer thickness and suggest the existence of bubblelike domainsâ€”potentially even magnetic skyrmionsâ€”in the case of sufficiently thick Mn layers, which are expected to contribute to a sizable Dzyaloshinskii-Moriya interaction in the multilayer stacks. We identify Pt/Co/Mn as a highly complex multilayer system with strong potential for further fundamental studies and possible applications [2]. This work is supported by the Deutsche Forschungsgemeinschaft (DFG) through the research fellowship LO 2584/1-1, the NSF through I-MRSEC Grant No. DMR-1720633 and US DOE, Office of Science, MSED under Contract No. DE-SC002260.

Structural and Magnetic Properties of Pt/Co/Mn Multilayers

Magnetocaloric materials are researched as promising alternatives to conventional gas compression technologies for heat conversion. Within the known magnetocaloric
materials, the MM'X system is promising as it features a strong first order magnetostructural transition (MST) enabled by partial substitution of M, M' and X sites, where M and M' are
transition metals and X is a p-block element in orthorhombic/hexagonal structures[1]. Commonly used intermetallics (MnNiGe, MnCoGe [2,3]) employ Ge and Co, which are critical for
their applications in electronics, and cathode materials for batteries, respectively. In the present study, Fe and Al substitutions inside a MnNiSi-based intermetallic induce a MST without
critical or expensive elements. All alloys have been synthesized by arc melting, and heat treated followed by quenching. By convenient substitution, the studied Mn1-xNi1-xFe2xSi0.95Al0.05
alloys exhibit Curie temperatures around room-temperature, which were captured by Vibrating Sample Magnetometry (VSM) as well as In-field differential scanning calorimetry (DSC)
[4]. The VSM magnetization over temperature data in the Mn0.69Ni0.69Fe0.62Si0.95Al0.05 sample with applied field μ0H = 1 T shown in Fig. 1 displays an abrupt variation of magnetization
with temperature, where the derivatives of magnetization exhibit a minimum between 279 and 290 K during cooling and heating, respectively. From the VSM measurements, what can be
thought of as a single-phase transition due to a single derivative minimum can be elucidated with the use of a 1K/min heating/cooling rate in the DSC. In fact, this MST is a convolution of
different transitions all close to one another, as shown during the cooling protocol in Fig. 2 from in-field DSC data with 1 T applied field. The main article will investigate the cause of such
distribution of transitions and its effect on the isothermal entropy change during heating and cooling transformations, as evaluated by a concurrent VSM and DSC study. 

**References:** 

[1] W. Bazela, A. Szytula, J. Todorovic, A. Zieba, Crystal and magnetic structure of the NiMnGe1−nSin System, Phys. Status Solidi. 64 (1981) 367–378.
https://doi.org/10.1002/pssa.2210640140. 
[2] A. Taubel, T. Gottschall, M. Fries, T. Faske, K.P. Skokov, O. Gutfleisch, Influence of magnetic field, chemical pressure and hydrostatic pressure on the structural and magnetocaloric
properties of the Mn-Ni-Ge system, J. Phys. D. Appl. Phys. 50 (2017). https://doi.org/10.1088/1361-6463/aa8e89. 
[3] S.K. Pal, C. Frommen, S. Kumar, B.C. Hauback, H. Fjellvåg, G. Helgesen, Enhancing giant magnetocaloric effect near room temperature by inducing magnetostructural coupling in
Cu-doped MnCoGe, Mater. Des. 195 (2020) 109036. https://doi.org/10.1016/j.matdes.2020.109036. 
[4] K.K. Nielsen, H.N. Bez, L. Von Moos, R. Bjørk, D. Eriksen, C.R.H. Bahl, Direct measurements of the magnetic entropy change, Rev. Sci. Instrum. 86 (2015).
https://doi.org/10.1063/1.4932308. 

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