Energy – one of the major crises humanity is facing in today’s modern life. There is a great interest in developing micro-scaled devices that can generate electricity using ambient radiofrequency (RF) energy without the need of any bias or magnetic field. We addressed this problem and used the intrinsic quantum property of the Weyl semimetal to convert the RF energy into electricity. The whole process is wireless and there is no need for any external electrical bias (battery-free) and magnetic field.
In this work, we report the room-temperature NLHE in a type-II Weyl semimetal TaIrTe4, which hosts a robust NLHE due to broken inversion symmetry and large band overlapping at the Fermi level. The NLHE is present only when the electric field is applied along the axis of the mirror plane (a-axis of the crystal). We also observe a temperature-induced sign inversion of NLHE in TaIrTe4. Finally, based on the observed room-temperature NLHE in TaIrTe4 we demonstrate the wireless RF rectification with zero external bias and magnetic field. As shown in Fig. 1(b), an incident electric field along a-axis (Ea) generates a rectified voltage along b-axis (Vb), whereas, there is no rectification when the incident electric field is along b-axis (Eb) in consistent with the symmetry constraints of NLHE. This work opens a door to realizing room temperature applications based on the NLHE in Weyl semimetals.


Room Temperature Nonlinear Hall Effect and Wireless RF Rectification in Weyl Semimetal TaIrTe4

In contrast to the Hall effect, the nonlinear Hall effect (NLHE) can produce a transverse voltage in zero magnetic field [1]. The NLHE is a second-order phenomenon, which exhibits two components; one is the voltage oscillating at twice the frequency 2ω of the driving alternating current and the other is a d.c. component that is generated due to the rectification effect. Therefore, the NLHE can be utilized in applications requiring frequency doubling or rectification such as energy harvesting, wireless communications and IR detectors [2,3]. However, it requires NLHE to be detected at room temperature. Despite of several studies of NLHE in topological materials and 2D materials, the room-temperature NLHE has not yet been achieved [4,5]. In this work, we report the room-temperature NLHE in a type-II Weyl semimetal TaIrTe4, which hosts a robust NLHE due to broken inversion symmetry and large band overlapping at the Fermi level. The NLHE is present only when the electric field is applied along the axis of the mirror plane (a-axis of the crystal). We also observe a temperature-induced sign inversion of NLHE in TaIrTe4. Our theoretical calculations suggest that the observed sign inversion is a result of temperature-induced shift in the chemical potential indicating a direct correlation of NLHE with the electronic structure at the Fermi surface. Finally, based on the observed room-temperature NLHE in TaIrTe4 we demonstrate the wireless RF rectification with zero external bias and magnetic field. As shown in Fig. 1(b), an incident electric field along a-axis (Ea) generates a rectified voltage along b-axis (Vb), whereas, there is no rectification when the incident electric field is along b-axis (Eb) in consistent with the symmetry constraints of NLHE. This work opens a door to realizing room temperature applications based on the NLHE in Weyl semimetals.

**References:**

[1] I. Sodemann and L. Fu, Phys. Rev. Lett., 115, p.216806 (2015) [2] H. Isobe, S.-Y. Xu, and L. Fu, Sci. Adv., 6, p.eaay2497 (2020) [3] G. Pacchioni, Nat. Rev. Mater., 4, p.514 (2019) [4] Q. Ma, S.-Y. Xu, H. Shen, Nature, 565, p.337 (2019) [5] K. Kang, T. Li, E. Sohn, Nat. Mater., 18, p.324 (2019)

**Images:**

![](https://assets.underline.io/uploads/markdown_image/1/image/1c5c29957fb9c4db9817e1c9249c7463.jpg)
Fig. 1. (a) Schematic of the rectifier fabricated on Td-TaIrTe4. Patch antenna with a high directivity and gain of 3 dBi at ~2.4 GHz is used for electromagnetic radiation. The Hall bar device, utilizing the room-temperature NLHE in TaIrTe4, rectifies the incident electric field along a-axis (Ea) and generates a d.c. along the transverse direction b-axis (Ib). (b) The rectified d.c. voltage measured along b-axis (Vb) as a function of frequency while aligning the incident electric field at four different angles (θ = 0°, 90°, 180°, and 270°) relative to a-axis as shown in the inset.

 Room Temperature Nonlinear Hall Effect and Wireless RF Rectification in Weyl Semimetal TaIrTe4

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