On the scaling of the (H-T)-phase diagram of CuGeO$_3$

TL;DR

This study maps the magnetic phase diagram of CuGeO3 under various pressures using optical spectroscopy, revealing deviations from existing theories and proposing a new scaling approach.

Contribution

It provides a detailed pressure-dependent phase diagram of CuGeO3 and introduces an alternative scaling method beyond the Cross-Fischer theory.

Findings

Phase diagrams do not follow Cross-Fischer scaling.

Optical absorption spectroscopy effectively detects phase transitions.

Proposed new scaling approach for the phase diagram.

Abstract

The H-T phase diagram of CuGeO$_3$ has been determined, for different values of the hydrostatic pressure, utilizing optical absorption spectroscopy on the Cu$^{2+}$ d-d transitions. It is shown that the intensity of the related zero phonon line transition is very sensitive to the local environment of Cu$^{2+}$, allowing for precise determination of all phase transitions. It is found that the phase diagrams at various pressures do not scale according to the Cross-Fischer theory. An alternative scaling is proposed.