Characterization of defect structures on triangular antiferromagnet PdCrO$_{2}$ using scanning tunneling microscopy and spectroscopy

Frustrated magnetic systems have received significant attentions due to the possibility as source of ferroelectricity. We studied atomic structures and electronic structures of defects in two dimensional triangular-lattice antiferromagnet PdCrO$_{2}$ using scanning tunneling microscopy and spectroscopy (STM / STS). In CrO$_{2}$ layers and Pd layers, atomic resolution STM images showed distinguishable defects and differential conductance images showed unusual standing wave patterns. We identified the origin of defect structures using STS measurements, atomic ball model analysis and Density Functional Theory (DFT) calculations. Atomic structure analysis of defects gives the opportunity to understand a ground state of frustrated magnetic materials.