Field-induced ordering in a random-bond quantum spin ladder compound with weak anisotropy

TL;DR

This study investigates how magnetic field-induced quantum phase transitions in a disordered spin ladder compound vary with field orientation, revealing different critical behaviors and challenging previous interpretations of the transition nature.

Contribution

It provides new insights into the anisotropic nature of quantum phase transitions in disordered spin ladders, emphasizing the role of field direction and disorder effects.

Findings

Different critical indexes for different field orientations.

Transition along the c axis resembles an Ising transition in random field.

Contrasts previous Bose Glass to Bose Condensate transition interpretation.

Abstract

The field induced quantum phase transitions in the disorder-free and disordered samples of the spin ladder material (CH_3)_2CHNH_3Cu(Cl_{1-x}Br_x)_3 are studied using magnetic calorimetry and magnetic neutron diffraction on single crystal samples. Drastically different critical indexes and correlation lengths in the high field phase are found for two different orientations of the applied field. It is argued that for a field applied along the crystallographic c axis, as in previous studies [1], the transition is best described as an Ising transition in random field and anisotropy, rather than as a magnetic Bose Glass to Bose Condensate transition. [1] Tao Hong, A. Zheludev, H. Manaka, and L.- P. Regnault, Phys. Rev. B 81, 060410 (2010).