Precision Measurements of Transverse Transport Coefficients by Torque Magnetometry
Abstract
Rationale: The discovery, understanding, and exploitation of new materials and phenomena are at the heart of modem materials science and materials physics. Invention and innovation in these fields have had a pervasive impact on our daily lives through revolutionary technological advances in information and energy applications. With new materials, some exhibiting subtle, yet profound characteristics, new methods for characterization are needed. Hall effect is one of the fundamental transport properties of solids which often reveal new physics that otherwise is hidden when other transport coefficients are measured. For start, it is the most direct signature of time reversal symmetry breaking is a solid. In addition, it is very sensitive to the microscopic scattering effect when the Hall conductivity is measured, but hardly sensitive to it, hence revealing fundamental properties of the material when the Hall resistivity is measured. Thus, introducing a new, highly sensitive, method to measure the Hall conductivity is potentially of great importance for present and future advances in solid state physics. lntellectual Merit: We propose a novel method to measure the Hall conductivity and other transverse transport effects in a variety of solid state systems using a Corbino-based geometry in conjunction with a cantilever based detection. Our method is based on perfect elimination of any longitudinal contamination of the electrical or thermal conductivities. It is also a direct measurement of Hall-conductivity and thus docs not need the inversion of the resistivity tensor to obtain this quantity. To elucidate our ideas and their relevance to many solid state systems we first give a comprehensive account of the Hall effect in a variety of experimentally available material systems, including metals, insulators, superconductors, and inhomogeneous systems composed of those three ingredients. This lead us to demonstrate that the method proposed in this proposal is particularly useful for sorting different topological states of matter where direct measurement of the Hall conductivity (rather than resistivity) is the important parameter. In addition, we note that direct measurement of the Hall conductivity is an important way to sort inhomogeneous conduction in two-dimensional structures and a sensitive way to measure quantum oscillations as a consequence of Landau level quantization. Broader Impact: We believe that the proposed work has the potential to impact science in several areas. First it will shed light on the nature of quantum phase transitions in reduced dimensions which is a fundamental problem in many subfields of physics. Second we believe that the effort that we have put into the fabrication will help us better understand the material science of the studied systems. Finally, the development of the proposed measurements methodologies are of general interest for the study of strongly correlated electron systems. The program proposes to involve graduate students in this area which is of great interest to physics and future applications. Statement of Work Summary: We propose a collaborative effort to develop a new technique and measurements methodology for high precision measurements of Hall effect. Using a Corbino-based geometry we are able to use torque magnetometry for measurements of the transverse current in the investigated material system. The work involves fabrication of cantilever devices with different types of sample mounting techniques, including direct deposition of thin film samples on the cantilever. Work at Stanford and Harvard will be complimentary. Cantilevers will be fabricated at Stanford, including in-situ thin-film samples deposition. Bulk samples mounting will be done at both institutions, Harvard and Stanford.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 16, 2018
- Source ID
- W911NF1710588
Entities
People
- Aharon Kapitulnik
Organizations
- Army Contracting Command
- Stanford University
- United States Army