Gate-tuned quantum Hall states in Dirac semimetal (Cd _{1− x} Zn _x ) ₃ As ₂

Abstract

Electronic structure of quantum-confined Dirac semimetal is elucidated by establishing carrier control techniques in films.

Observation of an Odd-Integer Quantum Hall Effect from Topological Surface States in Cd3As2

“…Lots of interesting transport properties have been revealed in 3D Dirac semimetals, such as chiral anomaly induced negative magnetoresistance [9,10], Weyl-orbit related quantum oscillations [13,14], Berry's phase π related Aharonov-Bohm effect [15,16], bulksurface interference induced Fano effect [19], etc. Furthermore, the quantum Hall effect (QHE) in Cd 3 As 2 films has been reported recently [20][21][22][23]. For Dirac materials, the quantum Hall plateaus are generally observed at g × ðn þ 1=2Þe 2 =h, where g is the degeneracy and the 1=2 term comes from the Berry's phase π [24].…”

“…However, the quantum Hall plateaus in Cd 3 As 2 were found to be a series of even filling factors υ ¼ 1; 2; 4; 6, where υ ¼ 1 is attributed to the splitting of the lowest Landau level [21,22]. Nishihaya et al attributed the observed QHE to the quantum confinement induced bulk subbands in the thin film with thickness ∼35 nm [20,22]. Schumann et al proposed that the QHE may from the Weyl orbit for the same film thickness ∼35 nm [21].…”

“…Thus, the filling factors can be a series of continuous integer values (both odd and even) or only odd series depending on the top and bottom surface carrier densities [25]. However, the quantum Hall plateaus in Cd 3 As 2 were found to be a series of even filling factors υ ¼ 1; 2; 4; 6, where υ ¼ 1 is attributed to the splitting of the lowest Landau level [21,22]. Nishihaya et al attributed the observed QHE to the quantum confinement induced bulk subbands in the thin film with thickness ∼35 nm [20,22].…”

“…Schumann et al proposed that the QHE may from the Weyl orbit for the same film thickness ∼35 nm [21]. Despite the debate on the mechanism of the QHE, the quantum Hall plateaus at even filling factors g × ne 2 =h with g ∼ 2 indicate the absence of the Berry's phase π or the topological nature [22].…”

Growth and Strain Engineering of Trigonal Te for Topological Quantum Phases in Non-Symmorphic Chiral Crystals

“…Gating has already been demonstrated in a previous section on unstrained, semiconducting nanowires. For the much more metallic Weyl semimetal phase in strained nanowires [6], effective gating is still possible with thin wires or with ionic liquid gating, as has been demonstrated in other metallic systems [68][69][70].…”