Singlet-triplet Crossover in the Two-dimensional Dimer Spin System YbAl3C3

TL;DR

This study investigates the magnetic behavior of YbAl3C3 at very low temperatures, revealing a singlet-triplet crossover in a narrow magnetic field range, indicating weak interdimer interactions in a nearly triangular lattice.

Contribution

First detailed low-temperature magnetization measurements of YbAl3C3 revealing the singlet-triplet crossover and metamagnetic transitions in this spin-gap system.

Findings

Metamagnetic transitions observed between 6-9 T for H // c

Magnetization saturates above 9 T for both field directions

Weak interdimer interactions suggested by narrow crossover field

Abstract

Low-temperature magnetization (M) measurements down to 0.1 K have been performed in magnetic fields up to 14.5 T for a single piece of a tiny single-crystalline sample (0.2 mg weight) of the spin-gap system YbAl3C3. At the base temperature of 0.1 K, several metamagnetic transitions were clearly observed for H // c in the range 6 T < H < 9 T whereas only two transitions were observed, one at 4.8 T and the other at 6.6 T, for H // a. At fields above 9 T, the magnetization becomes almost saturated for both H // a and H // c. The present results indicate that a singlet-triplet crossover occurs in a relatively narrow field range, suggesting a rather weak interdimer interaction in spite of the nearly triangular lattice of Yb ions.