Hidden spin-polarized bands in semiconducting 2H-MoTe₂

Abstract

We present experimental and theoretical studies of the electronic band structure of 2H-MoTe 2 at high hydrostatic pressures. Photoreflectance measurements allowed the determination of the pressure coefficient of the direct transitions A and B, which are 2.40(3) and −3.42(18) meV/kbar, respectively. We attribute the sign difference to a strong splitting of the conduction bands with increasing pressure and the presence of hidden spin-polarized states in bulk MoTe 2. These results provide direct experimental evidence that the spin-valley locking effect takes place in centrosymmetric transition metal dichalcogenides. IMPACT STATEMENT The experimental confirmation of the presence of spin-polarized states in a centrosymmetric crystal opens the door to explore valleytronic and spintronic phenomena beyond monolayers, including multilayers and heterostructures.

Unconventional Magnetism in Layered Transition Metal Dichalcogenides

“…The presence of such spin-polarized itinerant electrons would imply that these materials are dilute magnetic semiconductors. This idea may be partly supported by the recent report on the observation of hidden spin-polarized states in the bulk MoTe 2 [46]. Although the exact link between µSR and STM/DFT results [9] in 2H-MoTe 2 and 2H-MoSe 2 is not yet clear, both results together constitute a first strong evidence concerning the relevance of magnetic order in the TMDs physics.…”

Anisotropic optical properties of GeS investigated by optical absorption and photoreflectance

“…These include superconducting phenomena, large quantum efficiencies, large excitonic binding energies, or valley-and spin-degrees of freedom even in their bulk form. [2][3][4] All these exotic properties can be exploited in a wide range of optoelectronic and electronic applications, including transistors, photovoltaics, spintronics or nanoscale light-emitting devices. [5][6][7][8] Despite the associated vast technological interest, TMDs exhibit some fundamental constraints such as limited electron mobilities (below that of silicon) 9 or reduced band gap (typically below 2 eV), 10 which could hinder their implementation in many optoelectronic devices.…”

Valley polarization investigation of GeS under high pressure

“…Intensive research on 2D materials, such as transition-metal dichalcogenides (TMDs), revealed their remarkable electronic and optical properties. These include strong light-matter coupling [2], large excitonic binding energies, the easiness of producing heterostructures by stacking monolayers held by van der Waals (vdW) forces [3,4], as well as the presence of spin-polarized bands that couple to new degrees of freedom such as degenerate valleys or adjacent layers, even in their bulk form [5,6]. Despite the highly promising properties observed in TMDs for many optoelectronic and spintronic applications, alternative 2D materials with complementary properties are being researched.…”