Why zero-field quantized Hall effects survive only near one kelvin · revision history

Revision 2

Accepted · core change · record

Changes against revision 1:

Title
Why zero-field quantized Hall effects survive only near one kelvin
Plain
Magnetic topological insulators show a perfectly quantized Hall resistance only at temperatures of order one kelvin, far below the temperature at which they become magnetic, and the reason is debated.
Precise · changed · core
Revision 1: In Cr- or V-doped (Bi,Sb)2Te3 films and odd-layer MnBi2Te4 flakes, full quantum anomalous Hall quantization ($R_{xy} = h/e^2, R_{xx} \to 0$) appears only at $T$ of order 1 K, while magnetic order sets in at 10-30 K and spectroscopic exchange gaps of tens of meV are reported. Identify the mechanism limiting the quantization temperature (magnetic disorder and gap inhomogeneity, antisite defects, surface-gap fluctuations, parallel bulk conduction) and predict how to raise it. An answer quantitatively links measured disorder to the transport activation gap.
Revision 2: In Cr- or V-doped (Bi,Sb)2Te3 films and odd-layer $\mathrm{MnBi_2Te_4}$ flakes, full quantum anomalous Hall quantization ($R_{xy} = h/e^2, R_{xx} \to 0$) appears only at $T$ of order 1 K, while magnetic order sets in at 10-30 K and spectroscopic exchange gaps of tens of meV are reported. Identify the mechanism limiting the quantization temperature (magnetic disorder and gap inhomogeneity, antisite defects, surface-gap fluctuations, parallel bulk conduction) and predict how to raise it. An answer quantitatively links measured disorder to the transport activation gap.
Settled by
Local imaging of the exchange gap correlated with transport activation energies across samples, reproducing the quantization temperature.
Kind
phenomenon
Answer type
mechanism
References
(empty)
Literature status
open
Status note
(empty)
Posed since
(empty)

Decisions