Field-Induced Effects of Anisotropic Magnetic Interactions in SrCu2(BO3)2

TL;DR

This study investigates how anisotropic magnetic interactions influence the magnetic properties of SrCu2(BO3)2, revealing field-induced effects, anisotropic interactions, and their impact on quantum phase transitions and excitation gaps.

Contribution

The paper provides the first quantitative analysis of anisotropic interactions in SrCu2(BO3)2 using NMR, elucidating their role in singlet-triplet mixing and quantum phase transition suppression.

Findings

Determined intradimer Dzyaloshinsky-Moriya interaction and staggered g-tensor magnitudes.

Showed anisotropic interactions eliminate the expected quantum phase transition at Hc.

Accurately measured the excitation gap from nuclear relaxation rate activation energy.

Abstract

We observed a field-induced staggered magnetization in the 2D frustrated dimer-singlet spin system SrCu2(BO3)2 by 11B NMR, from which the magnitudes of the intradimer Dzyaloshinsky-Moriya interaction and the staggered g-tensor were determined. These anisotropic interactions cause singlet-triplet mixing and eliminate a quantum phase transition at the expected critical field Hc for gap closing. They also provide a quantitative account for some puzzling phenomena such as the onset of a uniform magnetization below the and the persistence of the excitation gap above Hc. The gap was accurately determined from the activation energy of the nuclear relaxation rate.