Using anisotropy as a probe for nematic order in the cuprates

Benjamin Phillabaum, Purdue University

Abstract

In this work we describe two methods for detecting electron nematics in the high Tc cuprates. In addition we also provide a method to analyze the behavior of the local nematic and determine the model which describes the nematic ordering. The first method is a two step Monte Carlo process which models a nematic as an Ising spin with quenched random field disorder and the phase of a superconductor as an XY model which has local anisotropy in its bond with nearest neighbors (due to the presence of a local nematic). Using this method we make predictions about the noise and the effects of an orienting on the anisotropy of the london penetration depth. Our second method is to use anisotropy in the local Fourier Transform of an STM image to extract the direction of a local nematic. We can apply this method to all points in the image and use cluster analysis to extract critical exponents, which will allow us to determine the behavior of the nematic in the bulk of the material. Finally we describe future work which can be achieved with these methods. We find that the nematicity in one direction is inversely proportional to the square of the london penetration depth along that direction. From our second method we find that the nematicity of a sample of Dy doped BiSrCaCuO acts as though it is near the random field fixed point.

Degree

Ph.D.

Advisors

Carlson, Purdue University.

Subject Area

Physics|Condensed matter physics

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