First-order antiferromagnetic transitions of SrMn2P2 and CaMn2P2 single crystals containing corrugated-honeycomb Mn sublattices
Date
2021-10-29
Authors
Sangeetha, N.S.
Pakhira, Santanu
Ding, Qing-Ping
Krause, Lennard
Lee, Hyung-Cheol
Smetana, Volodymyr
Mudring, Anja-Verena
Brummerstedt Iversen, Bo
Furukawa, Yuji
Johnston, David C.
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Iowa State University Digital Repository, Ames IA (United States)
Abstract
SrMn2P2 and CaMn2P2 are insulators that adopt the trigonal CaAl2Si2-type structure containing corrugated Mn honeycomb layers. Magnetic susceptibility chi and heat capacity versus temperature T data reveal a weak first-order antiferromagnetic (AFM) transition at the Neel temperature T-N = 53(1) K for SrMn2P2 and a strong first-order AFM transition at T-N = 69.8(3) K for CaMn2P2. Both compounds exhibit isotropic and nearly T-independent chi(T <= T-N), suggesting magnetic structures in which nearest-neighbor moments are aligned at approximate to 120 degrees to each other. The P-31 NMR measurements confirm the strong first-order transition in CaMn2P2 but show critical slowing down above T-N for SrMn2P2, thus also evidencing second-order character. The P-31 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)Mn-2 (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.
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IS-J 10632
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article
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This is a manuscript of an article published as Sangeetha, N. S., Santanu Pakhira, Qing-Ping Ding, Lennard Krause, Hyung-Cheol Lee, Volodymyr Smetana, Anja-Verena Mudring, Bo Brummerstedt Iversen, Yuji Furukawa, and David C. Johnston. "First-order antiferromagnetic transitions of SrMn2P2 and CaMn2P2 single crystals containing corrugated-honeycomb Mn sublattices." Proceedings of the National Academy of Sciences 118, no. 44 (2021): e2108724118.
DOI: 10.1073/pnas.2108724118.
Copyright 2021 The Authors.
DOE Contract Number(s): AC02-07CH11358.
Posted with permission.