Colossal magnetoresistance from spin-polarized polarons in an Ising system

Journal Article · 01 December 2024 · Proceedings of the National Academy of Sciences of the United States of America

DOI: https://doi.org/10.1073/pnas.2409846121 · OSTI ID:2479400

Li, Ying-Fei ^[1]; Been, Emily M. ^[1]; Balguri, Sudhaman ^[2]; Jia, Chun-Jing ^[3]; Mahendru, Mira B. ^[2]; Wang, Zhi-Cheng ^[2]; Cui, Yi ^[1]; Chen, Su-Di ^[4]; Hashimoto, Makoto ^[5]; Lu, Dong-Hui ^[5]; Moritz, Brian ^[1]; Zaanen, Jan ^[6]; Tafti, Fazel  ^[2]; Devereaux, Thomas P.  ^[7]; Shen, Zhi-Xun  ^[1]

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1. Stanford Institute for Materials and Energy Sciences, Stanford Linear Accelerator Center (SLAC) National Accelerator Laboratory, Menlo Park, CA 94025, Department of Applied Physics and Physics, Stanford University, Stanford, CA 94305, Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305
2. Departments of Physics, Boston College, Chestnut Hill, MA 02467
3. Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305, Department of Physics, University of Florida, Gainesville, FL 32611
4. Stanford Institute for Materials and Energy Sciences, Stanford Linear Accelerator Center (SLAC) National Accelerator Laboratory, Menlo Park, CA 94025, Department of Applied Physics and Physics, Stanford University, Stanford, CA 94305, Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305, Department of Physics, University of California, Berkeley, CA 94720
5. Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025
6. Institute Lorentz for Theoretical Physics, Leiden University, Leiden 2300 RA, Netherlands
7. Stanford Institute for Materials and Energy Sciences, Stanford Linear Accelerator Center (SLAC) National Accelerator Laboratory, Menlo Park, CA 94025, Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305

Recent experiments suggest a new paradigm toward novel colossal magnetoresistance (CMR) in a family of materials EuM ${}_2$ X ${}_2$ (M $=$ Cd, In, Zn; X $=$ P, As), distinct from the traditional avenues involving Kondo–Ruderman–Kittel–Kasuya–Yosida crossovers, magnetic phase transitions with structural distortions, or topological phase transitions. Here, we use angle-resolved photoemission spectroscopy and density functional theory calculations to explore their origin, particularly focusing on EuCd ${}_2$ P ${}_2$ . While the low-energy spectral weight royally tracks that of the resistivity anomaly near the temperature with maximum magnetoresistance ( $T_{\mathrm{MR}}$ ) as expected from transport-spectroscopy correspondence, the spectra are completely incoherent and strongly suppressed with no hint of a Landau quasiparticle. Using systematic material and temperature dependence investigation complemented by theory, we attribute this nonquasiparticle caricature to the strong presence of entangled magnetic and lattice interactions, a characteristic enabled by the $p$ - $f$ mixing. Given the known presence of ferromagnetic clusters, this naturally points to the origin of CMR being the scattering of spin-polarized polarons at the boundaries of ferromagnetic clusters. These results are not only illuminating to investigate the strong correlations and topology in EuCd ${}_2$ X ${}_2$ family, but, in a broader view, exemplify how multiple cooperative interactions can give rise to extraordinary behaviors in condensed matter systems.

• Research Organization: SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
• Sponsoring Organization: USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE); USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF)
• Grant/Contract Number: AC02-05CH11231; AC02-76SF00515; SC0023124
• OSTI ID: 2479400
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Issue: 50 Vol. 121; ISSN 0027-8424
• Publisher: Proceedings of the National Academy of SciencesCopyright Statement
• Country of Publication: United States
• Language: English