-dependence of spin exchange interactions in MnO ( = Rare-Earth Ions)

Kajimoto, Ryoichi; Mochizuki, Hidenori*; Yoshizawa, Hideki*; Shintani, Hiroshi*; Kimura, Tsuyoshi*; Tokura, Yoshinori*

Journal of the Physical Society of Japan, 74(9), p.2430 - 2433, 2005/09

https://doi.org/10.1143/JPSJ.74.2430

Magnon excitations have been investigated for PrMnO showing the -type antiferromagnetic ordering and TbMnO forming a long-period spin ordering by inelastic neutron scattering. Combined with a result of LaMnO [K.~Hirota ], the systematic data revealed that the ferromagnetic exchange interaction between nearest-neighbor (NN) Mn sites within the plane drastically decreases in MnO as the ionic radius of is reduced. In addition, finite next-nearest-neighbor (NNN) coupling is evident in TbMnO. In contrast, the exchange interaction along the axis shows much weaker dependence consistent with the Mn-O-Mn bond angle. These observations confirm a scenario that explains the evolution of spin structures in MnO in terms of the competition between the NN and NNN interactions [T.Kimura ].

Plasma Engineering Test Facility Conceptual Studies

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JAERI-M 8198, 94 Pages, 1979/04

JAERI-M-8198.pdf:2.31MB

no abstracts in English

Formation of ferromagnetic phase in nuclear grade austenitic stainless steel and evaluation based on system free energy

Shintani, Tsuyoshi*; Tsukada, Yuki*; Shiraki, Atsuhiro*; Murata, Yoshinori*; Morinaga, Masahiko*; Takaya, Shigeru; Koyama, Toshiyuki*

no journal, , 

The magnetic flux density of SUS316 changes lesser than that of SUS304 during creep deformation. In this study, the reason of this difference was investigated based on system free energy. As result, it was revealed that the strain energies of both steels, which contribute to the formation of ferromagnetic bcc phase, were almost the same. Therefore, the dependency of magnetic flux density change on steel grades will be related to that activation energy for the formation of ferromagnetic phase of SUS316 is larger than that of SUS304.