Metamagnetic Transition in UCoAl Probed by Thermoelectricity Measurements

TL;DR

This study investigates the thermoelectric and Nernst effects in UCoAl, revealing how the metamagnetic transition influences carrier effective mass and electronic behavior, with implications for understanding quantum criticality in itinerant magnets.

Contribution

It provides detailed thermoelectric measurements across the metamagnetic transition, highlighting changes in carrier properties and electronic states in UCoAl.

Findings

Effective mass of hole carriers changes at the metamagnetic transition.

No Fermi liquid behavior in the paramagnetic state down to 150 mK.

Field-induced ferromagnetic state shows Fermi liquid behavior.

Abstract

We report field and temperature dependent measurements of the thermoelectric power (TEP) and the Nernst effect in the itinerant metamagnet UCoAl. The magnetic field is applied along the easy magnetization c-axis in the hexagonal crystal structure. The metamagnetic transition from the paramagnetic phase at zero field to the field induced ferromagnetic (FM) state is of first order at low temperatures and becomes a broad crossover above the critical temperature $T^{\star}_{M} \sim 11$ K. The field-dependence of the TEP reveals that the effective mass of the hole carriers changes significantly at the metamagnetic transition. The TEP experiment reflects the existence of different carrier types in good agreement with band structure calculations and previous Hall effect experiments. According to the temperature dependence of the TEP, no Fermi liquid behavior appears in the paramagnetic state down to 150 mK, but is achieved only in the field induced ferromagnetic state.