GLAM Special Seminar
Geballe Laboratory for Advanced Materials
Wednesday, 22 May 2019 at 3:00 p.m.
Location: McCullough Building, Room #332
Host: Srinivas Raghu
Indian Institute for Technology (IIT), Madras
Griffiths phases in magnetic systems
Quenched disorder or "frozen-in" impurities play a very key role in determining the properties of material systems. This talk explores in a pedagogical manner the effects of disorder induced randomness in magnetic systems.
The talk will start with a short introduction to a classification scheme for disorder, and such well known concepts such as the heuristic derivation of the Harris criterion for random mass disorder and the Imry-Ma criterion for the random field systems.We will discuss the impact of these criterion in understanding the impact of impurities near classical transitions.We then specialize to the case of quantum phase transitions wherein we argue that disorder effects can be particularly severe on quantum phase transitions and lead to such exotic effects as Infinite randomness fixed point and Griffiths effects. It will also explore how the intriguing interplay of disorder and dissipation could lead to interesting phase transition scenarios in realistic systems like itinerant ferromagnets. Further, we will argue that such effects could plausibly be seen in classical systems with correlated disorder.