Colossal Room‐Temperature Terahertz Topological Response in Type‐II Weyl Semimetal NbIrTe₄

Abstract

The electromagnetic spectrum between microwave and infrared light is termed the “terahertz (THz) gap,” of which there is an urgent lack of feasible and efficient room‐temperature (RT) THz detectors. Type‐II Weyl semimetals (WSMs) have been predicted to host significant RT topological photoresponses in low‐frequency regions, especially in the THz gap, well addressing the shortcomings of THz detectors. However, such devices have not been experimentally realized yet. Herein, a type‐II WSM (NbIrTe4) is selected to fabricate THz detector, which exhibits a photoresponsivity of 5.7 × 104 V W−1 and a one‐year air stability at RT. Such excellent THz‐detection performance can be attributed to the topological effect of type‐II WSM in which the effective mass of photogenerated electrons can be reduced by the large tilting angle of Weyl nodes to further improve mobility and photoresponsivity. Impressively, this device shows a giant intrinsic anisotropic conductance (σmax/σmin = 339) and THz response (Iph‐max/Iph‐min = 40.9), both of which are record values known. The findings open a new avenue for the realization of uncooled and highly sensitive THz detectors by exploring type‐II WSM‐based devices.

2D Material Infrared Photonics and Plasmonics

“…Since the IR range corresponds to low photon energies (<1.55 eV), key 2D materials in such applications are normally narrow-bandgap semiconductors and semimetals (Figure ), such as graphene, , Group V materials such as black phosphorus (BP) , and black AsP, Group VI materials such as Bi 2 Se 3 , and tellurene, , transitional metal dichalcogenides (TMDCs) such as PtSe 2 , MoTe 2 , and WTe 2 , and ternary compounds including TaIrTe 4 and NbIrTe 4 . Semimetals, including graphene, Bi 2 Se 3 , MoTe 2 , WTe 2 , TaIrTe 4 , and NbIrTe 4 , have electronic band structures with linear Dirac cones.…”

Terahertz Nonlinear Hall Rectifiers Based on Spin‐Polarized Topological Electronic States in 1T‐CoTe2

“…[ 7 ] These open new possibilities for the development of dissipationless and ultrafast topological devices in data processing, sensing, and communication. [ 8 ] Therefore, photodetectors exploiting different light‐induced effects have recently been explored, including orbital‐selective photoexcitation, [ 9 ] large quantized circular photogalvanic effect, [ 10 ] and spatial dispersive circulating photocurrent effect, [ 11 ] leading to a significant injection/shift current contribution in the mid‐infrared regime. The substantial enhancement of the generated photocurrent was ascribed to the strong nonlinear effects associated with the geometric properties of the Bloch bands and the singularities of the Berry flux field at the Weyl nodes.…”

IrGe4: A Predicted Weyl-Metal with a Chiral Crystal Structure

“…For example, NCS Weyl semimetal TaIrTe 4 shows wireless radiofrequency rectification related to nonlinear Hall effect, and NbIrTe 4 exhibits a colossal terahertz topological response. 25,26 Apart from MIrTe 4 (M = Ta, Nb), there are no other NCS Ir-containing Weyl or Dirac metals/semimetals. Considering all crystal structures, there are only a few Ir-containing intermetallics reported to be Weyl or Dirac metals/semimetals, including Ir 2 In 8 Q (Q = S, Se, Te; P4 2 /mnm) with a large nonsaturating transverse magnetoresistance (MR), 27,28 and Ir 1−x Pt x Te 2 (0.1 < x < 0.4, P3̅ m1) even showing a superconducting state.…”

“…Reported Weyl metals/semimetals include MPn (M = Ta and Nb; Pn = P and As; space group I 4 1 md ), ,– MTe 2 (M = W and Mo; Pnm 2 1 ), , HgCr 2 Se 4 ( Fd 3̅ m ), Co 2 MnA (A = Al and Ga, Fm 3̅ m ), , RAlX (R = La, Ce, Pr, and Nd; X = Si and Ge; I 4 1 md ), , CoSi ( P 2 1 3), HfCuP ( P 3 m 1), EuAgP ( P 6 3 / mmc ), EuB 6 ( Pm 3̅ m ), EuMnSb 2 ( Pnma ), YbMnBi 2 ( P 4/ nmm ), Mn 3 X (X = Ge and Sn; P 6 3 / mmc ), , Co 3 Sn 2 S 2 ( R 3̅ m ), and MIrTe 4 (M = Ta and Nb; Pmn 2 1 ). , Nonmagnetic Weyl metals/semimetals adopt the noncentrosymmetric (NCS) crystal structure with inversion-symmetry broken (note that magnetic Weyl metals/semimetals can be NCS or centrosymmetric), which also provides opportunities to study the nonlinear optoelectronic phenomena and even ferroelectric switching in thin layers. For example, NCS Weyl semimetal TaIrTe 4 shows wireless radiofrequency rectification related to nonlinear Hall effect, and NbIrTe 4 exhibits a colossal terahertz topological response. , Apart from MIrTe 4 (M = Ta, Nb), there are no other NCS Ir-containing Weyl or Dirac metals/semimetals. Considering all crystal structures, there are only a few Ir-containing intermetallics reported to be Weyl or Dirac metals/semimetals, including Ir 2 In 8 Q (Q = S, Se, Te; P 4 2 / mnm ) with a large nonsaturating transverse magnetoresistance (MR), , and Ir 1– x Pt x Te 2 (0.1 < x < 0.4, P 3̅ m 1) even showing a superconducting state. , Inspired by these intriguing reports, we are motivated to discover more Ir-containing topological materials with an NCS crystal structure.…”