Measurements of spin–orbit interaction in epitaxially grown InAs nanosheets

Abstract

We report on a low-temperature transport study of a single-gate, planar field-effect device made from a free-standing, wurtzite-crystalline InAs nanosheet. The nanosheet is grown via molecular beam epitaxy and the field-effect device is characterized by gate transfer characteristic measurements and by magnetic field orientation dependent transport measurements. The measurements show that the device exhibits excellent electrical properties and the electron transport in the nanosheet is of the twodimensional nature. Low-field magnetoconductance measurements are performed for the device at different gate voltages and temperatures, and the characteristic transport lengths, such as phase coherent length, spin-orbit length and mean free path, in the nanosheet are extracted. It is found that the spin-orbit length in the nanosheet is short, on the order of 150 nm, demonstrating the presence of strong spin-orbit interaction in the InAs nanosheet. Our results show that epitaxially grown, free-standing, InAs nanosheets can serve as an emerging semiconductor nanostructure platform for applications in spintronics, spin qubits and planar topological quantum devices.

Electron transport properties of a narrow-bandgap semiconductor Bi2O2Te nanosheet

“…A theoretical study predicted that although it is natural to grow n-type Bi2O2Se, as-grown Bi2O2Te without doping should behave as an intrinsic semiconductor. 28 Figure 1(c) shows the measured longitudinal resistance 𝑅𝑅 xx and Hall resistance 𝑅𝑅 yx of our Bi2O2Te Hall-bar device at perpendicularly applied magnetic fields B and at 𝑇𝑇 = 2 K and 𝑉𝑉 g = 0 V. It is seen that 𝑅𝑅 xx displays a well-defined dip at low fields, i.e., a typical WAL characteristc, 11,25 revealing the presence of a strong SOI in the Bi2O2Te nanosheet. Here we note that similar WAL characteristics are also observed in other Hall-bar devices fabricated from thicker Bi2O2Te nanosheets (see Supplementary Materials).…”

“…Here, due to the fact that the device is made in a single-gate structure, it is hard to achieve a sufficiently large tuning of the electric field in the nanosheet. 11,25 The extracted 𝐿𝐿 e is ~8 nm and is also weakly dependent on Vg. This extracted value of 𝐿𝐿 e is consistent with the results determined above from the carrier density and mobility measurements shown in Fig.…”

“…Detailed low-field magnetotransport measurements are performed at different gate voltages and low temperatures. The measurements are analyzed based on a multi-channel Hikami-Larkin-Nagaoka (HLN) formula 11,[23][24][25] with taking the LMR correction into account 26,27 and the quantum transport characteristic parameters in the nanosheet are extracted. It is found that the spin relaxation length in the Bi2O2Te nanosheet is several times smaller than it in its counterpart Bi2O2Se nanoplate and thus an ultra-strong SOI is present in the Bi2O2Te nanosheet.…”

Electrically tunable spin–orbit interaction in an InAs nanosheet

“…Low-dimensional III-V narrow bandgap semiconductor nanostructures have attracted signicant interest due to their potential applications in nanoelectronics, 1,2 infrared optoelectronics, 3,4 spintronics, [5][6][7] and quantum electronics. [8][9][10][11][12][13] Among them, strong spin-orbit interaction (SOI) and large Landé gfactor have made InAs and InSb nanostructures widely used in realization of novel devices such as spin transistors, 14,15 spinorbit qubits, 16,17 and topological quantum devices. [18][19][20][21] The SOI originates from the nonrelativistic approach to the relativistic Dirac equation and describes that a moving (orbit) charged particle in an electric eld experiences an effective magnetic eld and thus the spin and momentum of the charged particle are coupled with the coupling strength being related to the electric eld.…”

“… 28 The preliminary study has experimentally demonstrated the existence of strong SOIs in the nanosheets. 9 However, due to the employment of a single-gate device configuration, the study has failed to reveal the origin and an efficient control of the SOI in the InAs nanosheets.…”