Inhomogeneous Kondo-lattice in geometrically frustrated Pr\(_{2}\)Ir\(_{2}\)O\(_{7}\)

Magnetic fluctuations induced by geometric frustration of local Ir-spins disturb the formation of long range magnetic order in the family of pyrochlore iridates, R\(_{2}\)Ir\(_{2}\)O\(_{7}\) (R = lanthanide)\(^{1}\). As a consequence, Pr\(_{2}\)Ir\(_{2}\)O\(_{7}\) lies at a tuning-free antiferromagn...

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Published in:arXiv.org 2021-01
Main Authors: Kavai, Mariam, Friedman, Joel, Sherman, Kyle, Gong, Mingda, Giannakis, Ioannis, Samad Hajinazar, Hu, Haoyu, Grefe, Sarah E, Leshen, Justin, Qiu, Yang, Nakatsuji, Satoru, Kolmogorov, Aleksey N, Si, Qimiao, Lawler, Michael, Aynajian, Pegor
Format: Article
Language:English
Subjects:
Cluster analysis
Clustering
Critical point
Density functional theory
Electron states
Entanglement
Fractal geometry
Hall effect
Kondo effect
Machine learning
Phase separation
Single crystals
Spin-orbit interactions
Tuning
Vector quantization
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Summary:Magnetic fluctuations induced by geometric frustration of local Ir-spins disturb the formation of long range magnetic order in the family of pyrochlore iridates, R\(_{2}\)Ir\(_{2}\)O\(_{7}\) (R = lanthanide)\(^{1}\). As a consequence, Pr\(_{2}\)Ir\(_{2}\)O\(_{7}\) lies at a tuning-free antiferromagnetic-to-paramagnetic quantum critical point and exhibits a diverse array of complex phenomena including Kondo effect, biquadratic band structure, metallic spin-liquid (MSL), and anomalous Hall effect\(^{2-5}\). Using spectroscopic imaging with the scanning tunneling microscope, complemented with machine learning K-means clustering analysis, density functional theory, and theoretical modeling, we probe the local electronic states in single crystal of Pr\(_{2}\)Ir\(_{2}\)O\(_{7}\) and discover an electronic phase separation. Nanoscale regions with a well-defined Kondo resonance are interweaved with a non-magnetic metallic phase with Kondo-destruction. Remarkably, the spatial nanoscale patterns display a correlation-driven fractal geometry with power-law behavior extended over two and a half decades, consistent with being in proximity to a critical point. Our discovery reveals a new nanoscale tuning route, viz. using a spatial variation of the electronic potential as a means of adjusting the balance between Kondo entanglement and geometric frustration.
ISSN:2331-8422
DOI:10.48550/arxiv.2006.07424