Physics 681: Frustration

Physics 681:
Frustration in Magnetism, Glasses and Quantum
Phase Transitions

Fall 2008
Serin 112
W 1:15 - 3:15 p.m

Course Instructor: Prof. Premi Chandra (pchandra@physics.rutgers.edu)

Overview: In this course I hope to introduce experimental and theoretical students to the central concept of frustration in condensed matter physics; we will explore its role in magnetism, glasses and in quantum phase transitions. In this class we will discuss three areas of current interest

-"moment-free" magnetism and quantum spin liquids
-glasses, complex free energy landscapes and optimization
-quantum vs. classical phase transitions

This course will be concept-based but technical details will be supplied when needed. We will connect our topics of study with current research through readings of both classic and current papers. More specifically I plan to link the topics to be explored with research areas of ongoing interest: frustration and multiferroics, spin glasses and their role in the study of small networks and finally quantum phase transitions and the emergence of new states of matter.

Premi Chandra

Syllabus

Week of	Topic	References
Sept. 3	Introduction/Overview
Sept. 10	Magnetic Frustration I Frustrated Magnets as Magnetic Refrigerants?	Geometric Frustration Enhanced Magnetocaloric Effect in Frustrated Magnets (theory) Magnetocaoric effect in pyrochlore antiferromagnet Gd2Ti2O7 (experiment)
Sept. 17	Magnetic Frustration II Do Quantum Spin Liquids really Exist?	Quantum Spin Liquids An End to the Drought of Quantum Spin Liquids Quantum Spin Liquids: A Flood or a Trickle? Spin Disorder on a Triangular Lattice
Sept. 24	Magnetic Frustration III More about Sighted Quantum Spin Liquids Spin Ice	Spin Dynamics and Spin Freezing in NiGa2S4 SL State in the Hyperkagome AFM Na4Ir3O8 Spin Ice Taking the Frustration out of Ice Zero-Point Entropy in Spin Ice
Oct. 1	Magnetic Frustration IV Are Magnetic Monopoles Present (and Observable) in Spin Ice?	Freedom for the Poles Elementary Excitations in Spin Ice Magnetic Monopoles in Spin Ice
Oct. 8	Magnetic Frustration V Are Magnetic Monopoles Present (and Observable) in Artifical 2d Spin Ice?	Great Moments in Disorder Artitificial Spin Ice Magnetostatic Interactions on a Square Lattice Magnetic Monopoles in 2D Spin Ice
Oct. 15	Multiferroics I Is Magnetic Frustration a Help or a Hindrance?	Multiferroics as Quantum Electromagnets Multiferroic and Magnetoelectric Materials Multiferroics: A Magnetic Twist for Ferroelectricity Magnetic Control of Ferroelectric Polarization
Oct. 22	Multiferroics II	Electric Control of Spin Helicity in a Magnetic Ferroelectric First Principles Study of Improper Ferroelectricity in TbMnO3 Spin-Orbit Coupling and Ion Displacements in Multiferroic TbMnO3 Multiferroics go High-Tc Cupric Oxide as an Induced-Multiferoric with high-Tc
Oct. 29	Spin Glasses I Frustration + Disorder = ??	Theory of Random Magnets Spin Glasses Spin Glass I, II, III, IV Insulating Spin-Glass System Eu{x} Sr{1-x}S Susceptibility of the Cu-Mn Spin Glass
Nov. 5	Spin Glasses II Spin-Offs	Spin Glass V, VI and VII Optimization with Simulated Annealing Machine Politics Travelling Salesman ( with Simulated Annealing) Applet
Nov. 10	More Glasses Biological Applications Real Glasses	The Statistical Mechanics of Neural Networks Neural Networks and Physical Systems with Emergent Collective Computational Abilities The Mysterious Glass Transition Note that class this week is on Monday Nov. 10th (not on Wed. 11/12)
Nov. 19	Quantum Glasses Quantum Annealing	Quantum Annealing in the Transverse Ising Model (theory) Quantum Annealing of a Disordered Magnet (expt) Quantum Annealing and Ananlog Quantum Computation
Nov. 24	Celebration of Frustration I Why is the Magnetism so Weak in the Iron Pnictides...is frustration important?	Magnetic Order close to Superconductivity in the Pnictides (expt) Magnetic Frustration and Anisotropy in High-Tc Iron Pnictides (theory) High-Temperature Superconductivity in the Iron Pnictides (overview) Probing Frustration through Neutron Scattering (Student Tutorial by Collin Broholm at HFM2008) Strong Correlations and Magnetic Frustration in the High Tc Iron Pnictides Note that class this week is on Monday Nov. 24th (not on Wed. 11/26)
Dec. 3	Celebration of Frustration II	Macroscopic Signature of Protected Spins in a Dense Frustrated Magnet (expt) Relaxor Ferroelectricity and Colossal Magnetocapacitive Coupling in Ferromagnetic CdCr2S4 (expt) Is CdCr2S4 a Multiferroic Relaxor? Ferroelectrics Go Bananas
Dec. 10	Celebration of Frustration III	Magnetic Properties of PaCdVO(PO4)2: A Strongly Frustrated Spin-1/2 Square Lattice Close to the Quantum Critical Regime (expt) Metallic Spin-Liquid Behavior of the Geometrically Frustrated Kondo Lattice Pr2Ir2O7 (expt)

A Collection of Current "Frustrated" Papers

Quantum and Classical Glass Transitions in LiHo{x}Y{1-x}F{4} (expt)

Spin-Glass Order Induced by Dynamic Frustration (expt)

Anisotropic-Driven Spin Glass in the Kagome Antiferromagnet... (expt)

Momentum Deficit in Quantum Glasses (theory)

Interplay of quantum paraelectricity and quantum magnetism in Li2ZrCuO4 (expt)

Slow Conductance Relaxations; Distringuishing the Electron Glass from Extrinsic Mechanisms (expt)

Frustrated Soft Modes and Negative Thermal Expansion in ZrW2O8 (expt)

The Electron Glass in a Switchable Mirror: Relaxation, Aging and Universality (expt)

Antiferromagnetic Order of the Iron Spins in NdOFeAs (expt)

Unconventional Spin Freezing and Fluctuations in the Frustrated Antiferromagnet NiGa2S2

Special Announcements

Have a Good Winter Break!