NMR of SmMn2Ge2 at high pressure

Lord, J.S.; Riedi, P. C.; Kapusta, Cz.; Buschow, K.H.J.

doi:10.1016/0921-4526(94)00466-9

Cited by 6 publications

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“…At T t2 Ϸ196 K there is a first order transition to an antiferromagnetic ͑AFM͒ state with Mn moments still lying along ͗001͘, and a further first order transition to a FM state ordered along ͗110͘ occurs at T t3 Ϸ100 K. On cooling the a axis contracts by ϳ0.15% at T t2 , and expands again by the same amount at T t3 , as investigated by Gyorgy et al 5 accuracy of their thermal expansion measurements was such that it is difficult to decide if the c axis also exhibits a jump at T t2 and T t3 but the jump is less than 0.08%. The best value for the magnetization at 4.2 K is probably 3.8 B , 6 although the value given in the original paper 7 is 4.18 B . Assuming the Sm NMR frequency at 4.2 K is consistent with that of a fully polarized Sm 3ϩ ion ͑with g J ϭ2/7, Jϭ5/2, ϭ0.71 B ), so a FM coupling to the Mn leads to a Mn moment of 1.55 B in the low temperature limit.…”

Section: Introductionmentioning

confidence: 90%

“…The effective field at the Sm nucleus in SmMn 2 Ge 2 in the low temperature limit is estimated to be 330 T, which may be compared with the free Sm 3ϩ ion value of 338 T. 6,10,12 The largest contribution to the Sm effective field comes from the orbital motion of the 4 f electrons of the parent atom which induces a field parallel to the magnetization. The 8 T discrepancy between SmMn 2 Ge 2 , and the free Sm 3ϩ ion value presumably arises from a transferred effective field from the Mn moments.…”

Section: Samarium Nmrmentioning

confidence: 98%

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NMR study of the ferromagnetic phases ofSmMn2Ge2as a function o

et al. 1996

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NMR study of the ferromagnetic phases of SmMn2Ge2 as a function of temperature and pressure Lord, J.S.; Riedi, P.C.; Tomka, G.J.; Kapusta, Cz.; Buschow, K.H.J. Link to publication Citation for published version (APA):Lord, J. S., Riedi, P. C., Tomka, G. J., Kapusta, C., & Buschow, K. H. J. (1996). NMR study of the ferromagnetic phases of SmMn2Ge2 as a function of temperature and pressure. Physical Review. B, Condensed Matter, 53(1), 283-288. DOI: 10.1103/PhysRevB.53.283 General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. The behavior of the reentrant ferromagnet SmMn 2 Ge 2 has been studied as a function of temperature and pressure using NMR in zero applied field. At atmospheric pressure SmMn 2 Ge 2 is ferromagnetic ͑FM͒ from T t1 Ϸ348 K to T t2 Ϸ196 K, then antiferromagnetic ͑AFM͒ to T t3 Ϸ100 K. The material is again ferromagnetic below T t3 . The behavior of T t3 as a function of pressure has been studied using 55 Mn NMR. The value of dT t3 /dP at low pressure is found to be about Ϫ16 K kbar Ϫ1 , in agreement with earlier work but its magnitude decreases at higher pressure. The value of T t3 at 7.8 kbar is 47 K. The 55 Mn NMR frequency increases with increasing temperature in the range 3-75 K, despite the decrease in magnetization by some 16%. The decrease in magnetization is attributed to the collapse of the ordered Sm state near 75 K. The 147 Sm and 149 Sm NMR could, however, only be observed up to 19 K, because of the rapid increase of the transverse relaxation rate with temperature, so we do not have conclusive evidence that the Sm moment has no influence on the AFM-FM transition at T t3 . A remarkable feature of the Sm NMR is that its frequency at a given temperature is independent of pressure whereas the Mn NMR frequency decreases with increasing pressure.

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Section: Introductionmentioning

confidence: 90%

Section: Samarium Nmrmentioning

confidence: 98%

NMR study of the ferromagnetic phases ofSmMn2Ge2as a function o

et al. 1996

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“…With further cooling of SmMn2Ge2 to 𝑇 Sm c (81 ∼ 112 K), [14,17] the Sm sublattice shows magnetic order, the sufficiently strong FM Sm-Mn coupling breaks the AFM Mn-Mn coupling, resulting in appearance of a re-entrant FM structure. [18,19] Notably, the spin texture of the Mn sublattice remains nonlinear from 𝑇c to the lowest temperature.…”

Section: (Received 16 April 2023; Accepted Manuscript Online 19 May 2...mentioning

confidence: 99%

Multiple Magnetic Phase Transitions and Critical Behavior in Single-Crystal SmMn₂Ge₂

Wang

Lin

Zeng

et al. 2023

Chinese Phys. Lett.

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Magnetic materials with noncolinear spin configurations have engendered significant interest in condensed matter physics due to their intriguing physical properties. In this study, we direct our attention towards the magnetic properties and critical behavior of single-crystal SmMn$_{2}$Ge$_{2}$, an itinerant magnet with numerous temperature-dependent magnetic phase transitions. Notably, SmMn$_{2}$Ge$_{2}$ displays significant magnetic anisotropy with easy magnetization direction switching from the $ c $ axis to the $ab$ plane as temperature decreases. The critical behavior of the ferromagnetic transition occurring above room temperature is thoroughly examined. Reliable and self-consistent critical exponents, including $ \beta = 0.292(2) $, $ \gamma=0.924(8) $, and $ \delta = 4.164(6)$, along with the Curie temperature, $T_{\rm c}=347$ K, are extracted through various methods, which provide evidence for the coexistence of multiple magnetic interactions in SmMn$_{2}$Ge$_{2}$. Further analysis reveals that the magnetic interaction of SmMn$_{2}$Ge$_{2}$ is a long-range type with the interaction distance decaying as $ J(r)\sim r^{-4.35} $.

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