Novel critical exponent of magnetization curves near the ferromagnetic quantum phase transitions of Sr1-xAxRuO3 (A = Ca, La0.5Na0.5, and La)

TL;DR

This paper reports a new critical exponent for magnetization near ferromagnetic quantum phase transitions in Sr1-xAxRuO3, challenging existing mean field theories and suggesting the importance of dirty ferromagnetic spin fluctuations.

Contribution

It identifies a novel critical exponent delta=3/2 for magnetization curves, which cannot be explained by traditional mean field theory.

Findings

Critical exponent delta=3/2 observed

Mean field theory fails to reproduce the results

Dirty ferromagnetic spin fluctuations may be key

Abstract

We report a novel critical exponent delta=3/2 of magnetization curves M=H^{1/delta} near the ferromagnetic quantum phase transitions of Sr1-xAxRuO3 (A = Ca, La0.5Na0.5, and La), which the mean field theory of the Ginzburg-Landau-Wilson type fails to reproduce. The effect of dirty ferromagnetic spin fluctuations might be a key.