Does the effective mass diverge at the 2D metal-insulator transition? · revision history

Revision 2

Accepted · core change · record

Changes against revision 1:

Title
Does the effective mass diverge at the 2D metal-insulator transition?
Plain
Near the transition, electrons in silicon devices behave as if they become many times heavier. Whether this effective mass (the mass that sets how electrons respond to forces) truly diverges at a critical density, and whether that density coincides with the transition, is unsettled.
Precise · changed · core
Revision 1: In low-disorder (100) Si-MOSFETs ($n_{\mathrm{c}} \sim 1e11\ \mathrm{cm}^{-2}$) and Si/SiGe quantum wells, determine whether m*(n), obtained from thermodynamic magnetization (d mu/d B) and from quantum oscillations, diverges as m*/m_b ~ (n - $n_m$)^(-alpha) at a finite density n_m; whether n_m equals $n_{\mathrm{c}}$ within error; and whether the spin susceptibility g* m* diverges at the same density (flat-band versus Stoner-type instability).
Revision 2: In low-disorder (100) Si-MOSFETs ($n_{\mathrm{c}} \sim 10^{11}\ \mathrm{cm}^{-2}$) and Si/SiGe quantum wells, determine whether m*(n), obtained from thermodynamic magnetization (d mu/d B) and from quantum oscillations, diverges as m*/m_b ~ (n - $n_m$)^(-alpha) at a finite density n_m; whether n_m equals $n_{\mathrm{c}}$ within error; and whether the spin susceptibility g* m* diverges at the same density (flat-band versus Stoner-type instability).
Settled by
Independent thermodynamic and quantum-oscillation measurements of $m*$ in samples of different disorder, showing whether $n_m$ is disorder independent and equal to $n_c$.
Kind
well-posed
Answer type
yes-no
References
(empty)
Literature status
contested
Status note
Shashkin, Kravchenko and coworkers report a strong mass enhancement tending to diverge near $n_{c}$ in Si systems (2000s to 2021); independent confirmation of a true divergence is lacking.
Posed since
(empty)

Decisions