Heat Capacity Evidence for the Suppression of Skyrmions at Large Zeeman Energy

TL;DR

This study shows that increasing Zeeman energy suppresses Skyrmion excitations in a 2D electron system, evidenced by the disappearance of nuclear spin heat capacity contributions at a critical energy ratio.

Contribution

It provides experimental evidence for the suppression of Skyrmions at large Zeeman energies, highlighting a transition from Skyrmions to single spin-flip excitations in a 2DES.

Findings

Nuclear spin heat capacity contribution vanishes above a critical Zeeman energy ratio.

Critical ratio $ ilde{g}_c$ observed is smaller than theoretical predictions.

Transition from Skyrmions to single spin-flip excitations identified.

Abstract

Measurements on a multilayer two-dimensional electron system (2DES) near Landau level filling $\nu$=1 reveal the disappearance of the nuclear spin contribution to the heat capacity as the ratio $\tilde{g}$ between the Zeeman and Coulomb energies exceeds a critical value $\tilde{g}_c \approx$0.04. This disappearance suggests the vanishing of the Skyrmion-mediated coupling between the lattice and the nuclear spins as the spin excitations of the 2DES make a transition from Skyrmions to single spin-flips above $\tilde{g}_c$. Our experimental $\tilde{g}_c$ is smaller than the calculated $\tilde{g}_c$=0.054 for an ideal 2DES; we discuss possible origins of this discrepancy.