Real-space observation of emergent complexity of phase evolution in micrometer-sized IrTe$_2$ crystals

TL;DR

This study uses real-space scanning Raman microscopy to observe complex phase evolution in micrometer-sized IrTe$_2$ crystals, revealing variability and emergent coexistence of superconducting phases due to size effects.

Contribution

It provides the first real-space observation of complex, size-dependent phase evolution and emergent superconductivity in IrTe$_2$ thin flakes, challenging statistical models.

Findings

Phase evolution involves growth of few domains, not many as in statistical models.

Variability in phase behavior is observed across specimens and measurements.

Emergence of superconducting phase without chemical doping in small specimens.

Abstract

We report complex behaviors in the phase evolution of transition-metal dichalcogenide IrTe$_2$ thin flakes, captured with real-space observations using scanning Raman microscopy. The phase transition progresses via growth of a small number of domains, which is unlikely in statistical models that assume a macroscopic number of nucleation events. Consequently, the degree of phase evolution in the thin flakes is quite variable for the selected specimen and for a repeated measurement sequence, representing the emergence of complexity in the phase evolution. In the $\sim$20-$\mu$m$^3$-volume specimen, the complex phase evolution results in the emergent coexistence of a superconducting phase that originally requires chemical doping to become thermodynamically stable. These findings indicate that the complexity involved in phase evolution considerably affects the physical properties of a small-sized specimen.