Phase diagram and quantum oscillations of RAgSb2 R$=$(La, Gd)

POSTER

Abstract

Previous research suggests an association between~high-temperature~superconductivity and a quantum critical point arising from suppression of the magnetic and/or structural phase transitions~via chemical doping. Here, we explore a chemical doping sequence of~LaAgSb$_{\mathrm{2}}$ and GdAgSb$_{\mathrm{2}}$~to study a similar phase competition found in many~copper-based and~iron-based~high-temperature superconductors. Systematic measurements of the resistivity, susceptibility, and quantum oscillations are presented~for single-crystal samples of the~chemically substituted~RAgSb$_{\mathrm{2}}$~(R$=$Gd,La). Doping the parent compound LaAgSb$_{\mathrm{2}}$~with Gd explores the effect of~magnetic doping and~applying chemical pressure to~the crystal. La$_{\mathrm{1-x}}$Gd$_{\mathrm{x}}$AgSb$_{\mathrm{2~}}$exhibits charge density ordering around that is suppressed with increase Gd percentages, while Gd$_{\mathrm{1-x}}$Y$_{\mathrm{x}}$AgSb$_{\mathrm{2}}$~exhibits anti-ferromagnetic ordering that is suppressed with increasing Y percentages. Resistivity and susceptibility data are used to identify phase transition temperatures and create a temperature vs doping phase diagram for each chemical substitution family. These diagrams show a strong suppression of charge density waves with magnetic gadolinium doping and the appearance of an antiferromagnetic state, with no apparent coexistence of charge and magnetic ordering. Additionally, magnetic quantum oscillation data are presented showing the changes in the Fermi surface and effective mass with chemical doping.

Authors

  • Anna Roche

    University of Washington

  • D. Niroomand

    Gonzaga University, Wabash College, Simon Fraser University, Tel Aviv University, University of Manitoba, Texas A&M University, TRIUMF, University of British Columbia, Caltech, Western Washington University, University of Washington, Whatcom Community College, Smithsonian Astrophysical Observatory, Siena College, University of Idaho, Department of Mechanical Engineering, University of Idaho, Boise State University

  • D. Niroomand

    Gonzaga University, Wabash College, Simon Fraser University, Tel Aviv University, University of Manitoba, Texas A&M University, TRIUMF, University of British Columbia, Caltech, Western Washington University, University of Washington, Whatcom Community College, Smithsonian Astrophysical Observatory, Siena College, University of Idaho, Department of Mechanical Engineering, University of Idaho, Boise State University