Magnetic Phase Diagram of the Breathing Pyrochlore Antiferromagnet LiGa1-xInxCr4O8

TL;DR

This study explores the magnetic phase diagram of breathing pyrochlore antiferromagnets LiGa1-xInxCr4O8, revealing how doping influences magnetic transitions, spin-glass behavior, and spin-gap phenomena, highlighting the role of geometrical frustration and bond alternation.

Contribution

It provides the first detailed phase diagram of LiGa1-xInxCr4O8, demonstrating how doping suppresses magnetic transitions and induces diverse magnetic states, emphasizing the significance of breathing pyrochlore structures.

Findings

Rapid suppression of magnetic and structural transitions with doping.

Observation of spin-glass-like freezing in certain doping ranges.

Detection of spin-gap behavior at high In content.

Abstract

The spinel oxides LiGaCr4O8 and LiInCr4O8 contain size-alternating pyrochlore lattices of spin-3/2 Cr3+ tetrahedra with different magnitudes of alternation. We show here that the solid solutions LiGa1-xInxCr4O8 between these two 'breathing' pyrochlore compounds display (i) rapid suppression of magnetic and structural transitions upon doping the end members, (ii) spin-glass-like freezing above 2 K in the range 0.1 $\lesssim$ x $\lesssim$ 0.6, and (iii) apparent spin-gap behavior for x $\gtrsim$ 0.7. Furthermore, no transitions are observed above 2 K at x ~ 0.9, where magnetic susceptibility remains finite at 2 K and magnetic heat capacity shows a quadratic temperature dependence at 1-5 K. Our work shows that breathing pyrochlore compounds provide a unique opportunity for studying both geometrical frustration and bond alternation.