著者

Yamada Isao

出版者

一般社団法人日本物理学会

雑誌

Journal of the Physical Society of Japan (ISSN:00319015)

巻号頁・発行日

vol.33, no.4, pp.979-988, 1972-10-05

被引用文献数

4 198

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It has been found that K_2CuF_4 is ferromagnetic below 6.25K. The two-dimensionality of this compound as expected from its K_2NiF_4 type structure is strongly supported by magnetic and specific heat measurements. The torque as well as zero field NMR measurements suggest that the c-plane is an easy plane, in which the spins are very weakly bounded to the direction of a-axia. On the assumption that this magnetic system to be purely two-dimensional, the exchange interaction J between tha spins within the c-plane is found to be the Heisenberg type with about one percent XY-like anisotropy and j/k=10.0K is obtained from the series expansion analysis of the high temperature susceptibility as well as linear dependence of the low temperature specific heat. The transition at 6.25K may be caused by inter-layer exchange interaction. The exchange field between the adjacent layers is expected at least larger than 400 Oe.