Date of Degree

9-2018

Document Type

Dissertation

Degree Name

Ph.D.

Program

Physics

Advisor

Myriam P. Sarachik

Committee Members

Michael L. Baker

Eugene M. Chudnovsky

Joel I. Gersten

Sergey Vitkalov

Subject Categories

Condensed Matter Physics

Keywords

Molecular magnet, Dy

Abstract

Molecular magnets (MM) are finite clusters of identical exchange-coupled magnetic systems arranged within a crystalline array such that interactions between neighboring MMs are negligible. Their small size has proven them amenable test beds for the investigation of a wide range of fundamental quantum phenomena such as spin frustration quantum tunneling (QT) of magnetization and Neel vector quantum coherence and Berry phase interference.

Cases where MMs have been found to exhibit quantum wave-functions that evolve coherently are particularly interesting due to their potential for use in quantum information processing. Toroidal magnetic moments, a kind of MM, have fascinating properties that could prove them to be important ingredients for future data storage and other information technology applications.

The toroidal magnetic moment is characterized by vortex distributions of magnetic dipoles. A classical example is a ring-shaped torus with current windings. Molecular materials offer much richer possibilities for the design of multicentre systems with desired non-collinear arrangement of magnetic moments.

Investigations of such molecules have entailed theoretical calculations and mainly powder sample measurements. Magnetic measurements have generally been insufficient to draw any conclusion about the toroidal nature in the ground state without ab initio calculations. In this thesis, we report measurements of the angular dependence of magnetization of (Et4N)4[Dy8O(nd)8(NO3)10(H2O)2]2MeCN (Dy8) which provide strong evidence for a toroidal ground state in this molecular magnet.

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