Date of Degree

9-2015

Document Type

Dissertation

Degree Name

Ph.D.

Program

Physics

Advisor(s)

Vadim Oganesyan

Committee Members

Eugene Chudnovsky

Dmitry Garanin

Pouyan Ghaemi

Steven Girvin

Tobias Schafer

Subject Categories

Condensed Matter Physics | Physics

Keywords

Ising model; LiHoF4; mean field theory; quantum criticality

Abstract

In this dissertation, I study the magnetic properties of LiHoF4. Quantum criticality in rare earth ferromagnet LiHoF4 is complicated by the presence of strong crystal field and hyperfine interactions resulting, e.g., in incomplete mode softening reported by Rønnow et al. We construct a systematic framework for treating elementary excitations in this material across the phase diagram. These excitations interpolate between purely electronic, nuclear and lattice modes and exhibit two-types of quantum critical softening, both complete (as anticipated by elementary treatments, see e.g. Sachdev) but also incomplete, in close correspondence with nuclear scattering results.

 
 

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