Critical properties of the S=1 spin dimer compound Ba3Mn2O8

TL;DR

This study investigates the quantum critical behavior of the S=1 spin dimer compound Ba3Mn2O8 using NMR spectroscopy, revealing its phase transitions and critical properties consistent with Bose-Einstein condensation and Ising models.

Contribution

The paper provides experimental evidence and theoretical modeling of the critical properties of Ba3Mn2O8 near its quantum critical point, highlighting its behavior as a dilute boson gas and Ising-like system.

Findings

Identification of the lower critical field Hc1 for different field orientations

Measurement of magnetizations near the quantum critical point

Agreement of experimental data with low-energy bosonic models

Abstract

Ba3Mn2O8 is a hexagonally coordinated Mn5+ S=1 spin dimer system with small uniaxial single-ion anisotropy. 135,137Ba NMR spectroscopy is used to establish the lower critical field Hc1 of distinct field-induced phases for H parallel to c,H perpendicular to c, and measure the longitudinal (Ml) and transverse (Mt) magnetizations in the vicinity of the quantum critical point (QCP). Ml_parallel (T, Hc1), Ml_perpendicular (T, Hc1) are reproduced by solving a low-energy model for a dilute gas of interacting bosons. Ml_parallel(T goes to 0, H = Hc1) (Ml_perpendicular(T goes to 0, H = Hc1)) follows the expectation for a BEC (Ising-like) QCP.