Magnetic-field-induced ordered phase in the chloro-bridged copper(II) dimer system [Cu2(apyhist)2Cl2](ClO4)2

TL;DR

This study investigates a copper-based compound that exhibits a magnetic-field-induced antiferromagnetic ordered phase at very low temperatures, with properties consistent with Bose-Einstein Condensation of magnetic excitations, and presents its phase diagram.

Contribution

The paper reports the discovery and analysis of a magnetic-field-induced ordered phase in a copper dimer system, demonstrating BEC behavior and providing the phase diagram with a notably low critical magnetic field.

Findings

Identification of a magnetic-field-induced antiferromagnetic phase at low temperatures and fields

Analysis showing the phase as a Bose-Einstein Condensation of magnetic excitations

The compound has one of the lowest critical fields among BEC quantum magnets

Abstract

Specific heat and magnetization measurements of the compound [Cu2(apyhist)2Cl2](ClO4)2, where apyhist = (4-imidazolyl)ethylene-2-amino-1-ethylpyridine), were used to identify a magnetic-field-induced long-range antiferromagnetic ordered phase at low temperatures (T < 0.36 K) and magnetic fields (1.6 T < H < 5.3 T). This system consists of a Schiff base copper(II) complex, containing chloro-bridges between adjacent copper ions in a dinuclear arrangement, with an antiferromagnetic intradimer interaction |Jintra|/kB = 3.65 K linked by an antiferromagnetic coupling |Jinter|z/kB = 2.7 K. The magnetic-field-induced ordering behavior was analyzed using the mean field approximation and Monte Carlo simulation results. The obtained physical properties of the system are consistent with the description of the ordered phase as a Bose-Einstein Condensation (BEC) of magnetic excitations. We present the phase diagram of this compound, which shows one of the lowest critical magnetic field among all known members of the family of BEC quantum magnets.