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First-order antiferromagnetic transitions of SrMn2P2 and CaMn2P2 single crystals containing corrugated-honeycomb Mn sublattices

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  • N. S. Sangeetha, Iowa State University
  • ,
  • Santanu Pakhira, Iowa State University
  • ,
  • Qing Ping Ding, Ames Laboratory, Iowa State University
  • ,
  • Lennard Krause
  • Hyung Cheol Lee, Iowa State University, Ames Laboratory
  • ,
  • Volodymyr Smetana, Stockholm University
  • ,
  • Anja Verena Mudring
  • Bo Brummerstedt Iversen
  • Yuji Furukawa, Iowa State University
  • ,
  • David C. Johnston, Iowa State University

SrMn2P2 and CaMn2P2 are insulators that adopt the trigonal CaAl2Si2-type structure containing corrugated Mn honeycomb layers. Magnetic susceptibility X and heat capacity versus temperature T data reveal a weak first-order antiferromagnetic (AFM) transition at the Néel temperature TN = 53(1) K for SrMn2P2 and a strong first-order AFM transition at TN = 69.8(3) K for CaMn2P2. Both compounds exhibit isotropic and nearly T-independent X(T ≤ TN), suggesting magnetic structures in which nearestneighbor moments are aligned at ≈120° to each other. The 31P NMR measurements confirm the strong first-order transition in CaMn2P2 but show critical slowing down above TN for SrMn2P2, thus also evidencing second-order character. The 31P NMR measurements indicate that the AFM structure of CaMn2P2 is commensurate with the lattice whereas that of SrMn2P2 is incommensurate. These first-order AFM transitions are unique among the class of (Ca, Sr, Ba)Mn2 (P, As, Sb, Bi)2 compounds that otherwise exhibit second-order AFM transitions. This result challenges our understanding of the circumstances under which first-order AFM transitions occur.

Original languageEnglish
Article numbere2108724118
JournalProceedings of the National Academy of Sciences of the United States of America
Number of pages8
Publication statusPublished - Nov 2021

Bibliographical note

Publisher Copyright:
© 2021 National Academy of Sciences. All rights reserved.

    Research areas

  • CaMn2P2, First-order antiferromagnetic transitions, Incommensurate and commensurate antiferromagnetic structures, SrMn2P2, Trigonal CaAl2Si2 structure, incommensurate and commensurate antiferromagnetic structures, RELAXATION, 4-COMPONENT VECTOR MODELS, first-order antiferromagnetic transitions, PHYSICAL REALIZATIONS, MAGNETISM, PARAMAGNETIC TRANSITION, trigonal CaAl2Si2 structure, PHASE-TRANSITION, CAAL2SI2 STRUCTURE

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