Spin states in InAs/AlSb/GaSb semiconductor quantum wells

Li, Jun; Yang, Wen; Chang, Kai

doi:10.1103/physrevb.80.035303

Cited by 45 publications

(51 citation statements)

References 52 publications

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“…The PB model is based on an eight-band k · p method, described in the literature 21,[23][24][25][26][27] , which has been successfully used for achieving semi-quantitative understanding of the electronic and magneto-optical properties of narrow-gap semiconductors [28][29][30][31] . We paid special attention to two important effects: (1) the effect of strain due to the lattice mismatch among different QW layers, and (2) the effect of charge transfer through the InAs/GaSb interface.…”

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Probing the semiconductor to semimetal transition in InAs/GaSb double quantum wells by magneto-infrared spectroscopy

et al. 2017

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We perform a magneto-infrared spectroscopy study of the semiconductor to semimetal transition of InAs/GaSb double quantum wells from the normal to the inverted state. We show that owing to the low carrier density of our samples (approaching the intrinsic limit), the magneto-absorption spectra evolve from a single cyclotron resonance peak in the normal state to multiple absorption peaks in the inverted state with distinct magnetic field dependence. Using an eight-band Pidgeon-Brown model, we explain all the major absorption peaks observed in our experiment. We demonstrate that the semiconductor to semimetal transition can be realized by manipulating the quantum confinement, the strain, and the magnetic field. Our work paves the way for band engineering of optimal InAs/GaSb structures for realizing novel topological states as well as for device applications in the terahertz regime.

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Probing the semiconductor to semimetal transition in InAs/GaSb double quantum wells by magneto-infrared spectroscopy

et al. 2017

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“…2). To what extent such anisotropy would affect the gap value is a subject for numerical calculations with realistic materials parameters 17 …”

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Finite conductivity in mesoscopic Hall bars of inverted InAs/GaSb quantum wells

Knez

Sullivan

2010

Phys. Rev. B

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We have studied experimentally the low temperature conductivity of mesoscopic size InAs/GaSb quantum well Hall bar devices in the inverted regime. Using a pair of electrostatic gates we were able to move the Fermi level into the electron-hole hybridization state, and observe a mini gap. Temperature dependence of the conductivity in the gap shows residual conductivity, which can be consistently explained by the contributions from the free as well as the hybridized carriers in the presence of impurity scattering, as proposed by Naveh and Laikhtman [Euro. Phys. Lett., 55, 545-551 (2001)]. Experimental implications for the stability of proposed helical edge states will be discussed. It was recently proposed by Kane and Mele 1, and independently, by Bernevig and Zhang 2 that a novel transport phenomenon, termed the quantum spin Hall effect (QSHE) should arise in a class of two-dimensional topological insulators (TI). The QSHE phase is characterized by an odd number of Kramer pair states at the edges, and an insulating gap in the bulk. Edge states are robust against disorder due to the topology of the bands and result in helical edge transport with counterpropagating spin-up and spin-down channels. Four-probe transport measurements on such structures at zero magnetic field give a near quantized conductance of 2e 2 /h for mesoscopic samples. Just as theoretically predicted by Bernevig et al , giving rise to a phase transition from a normal insulator to TI via a continuously varying parameter.In CQW, carriers (electrons and holes) are separated in different wells and the bulk energy gap arises due to the hybridization of the e-and the h-bands at a finite k-vector in momentum space. This finite k character is in contrast to that in the HgTe QWs, where the carriers are in the same well and the energy gap opens in the zone center. It is theoretically realized that disorder (which always exists in real materials) could play different roles in the two cases 7 for the experimental observation of QSHE. In this paper we present an experimental study of lowtemperature conductivity in mesoscopic size CQW Hallbar devices. Analyses of our results indicate intricate contributions from the free as well as the hybridized carriers to the bulk CQW conductivity in the presence of a finite amount of disorder. Interestingly, such contributions appear to be independent of the amount of scattering but vary strongly with CQW band parameters corroborated the existence of a tunneling-induced mini-gap. These results convincingly show that a mini-gap exists due to e-h hybridization in the inverted regime of InAs/GaSb CQWs. In contrast, a true bulk insulator, which shows temperature activated conductivity has yet to be experimentally confirmed. Moreover, in light of the current interest in observing the QSHE, transport in the mesoscopic-size devices should be measured 4 . Work reported here presents a first experimental study in this direction.InAs/GaSb CQW was grown by molecular beam epitaxy on silicon-doped N + (100) GaAs substrate. The structu...

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“…Therefore, although our calculation is based on a simple four band model, all the arguments should remain valid qualitatively in realistic materials. Quantitatively, to determine the regime of the QAH effect, we perform an electronic band structure calculation with an eight-band Kane model 49,50 . The band gap as a function of d InAs and spin of magnetic atom S M is plotted in Fig.4, from which we can extract the phase diagram.…”

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Quantum Anomalous Hall Effect in Magnetically Doped InAs/GaSb Quantum Wells

et al. 2014

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The quantum anomalous Hall effect has recently been observed experimentally in thin films of Cr doped (Bi,Sb)2Te3 at a low temperature (∼ 30mK). In this work, we propose realizing the quantum anomalous Hall effect in more conventional diluted magnetic semiconductors with doped InAs/GaSb type II quantum wells. Based on a four band model, we find an enhancement of the Curie temperature of ferromagnetism due to band edge singularities in the inverted regime of InAs/GaSb quantum wells. Below the Curie temperature, the quantum anomalous Hall effect is confirmed by the direct calculation of Hall conductance. The parameter regime for the quantum anomalous Hall phase is identified based on the eight-band Kane model. The high sample quality and strong exchange coupling make magnetically doped InAs/GaSb quantum wells good candidates for realizing the quantum anomalous Hall insulator at a high temperature.

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Spin states in InAs/AlSb/GaSb semiconductor quantum wells

Cited by 45 publications

References 52 publications

Probing the semiconductor to semimetal transition in InAs/GaSb double quantum wells by magneto-infrared spectroscopy

Probing the semiconductor to semimetal transition in InAs/GaSb double quantum wells by magneto-infrared spectroscopy

Finite conductivity in mesoscopic Hall bars of inverted InAs/GaSb quantum wells

Quantum Anomalous Hall Effect in Magnetically Doped InAs/GaSb Quantum Wells

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