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102. Paramagnetic relaxation in nickel fluosilicate
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occurs in a restricted range of magnetic fields; in this same range double relaxation effects are found (of. 8) 4)). All these anomalous effects show a marked crystalline anisotropy. I n the 1 : 40 diluted crystals the specific heat anomalies and double relaxations are absent. This m a y suggest t h a t they have to do with interactions between nearest neighbours. I n the silico fluoride crystals (1 : 0 and 1 : 10) no anomalous behaviour has been found. 1) 2) 3) 4)
Benzie, R..J., Cooke, A. H. and Whitley, S., Proc. roy Soc. 232 (1955) 277. Hascda, T. and Kanda, ]E., Physica 22 (1956) 647. Van der Marel, L. C., thesis Leiden 1958. See L. C. Van der Marel's abstract at this conference (No. 98).
101. Pararnagnetic R e l a x a t i o n in Cobaltous Salts at Liquid H e l i u m T e m p e r a tures. T. H A S E D A and E: KANDA.
The Research Institute for Iron, Steel and Other IVfetals, TShoku University, Sendal, Japan. We have measured paramagnetic relaxation in some cobaltous salts at liquid helium temperatures and found an anomaly in the field dependence of spin-lattic relaxation time such as dpsL/dHc < O. Salts examined, are CoNH4-Tutton, CoK-Tutton, COSO4.7H20, CoI2.9H~O, CoSiF8.6H20, etc. I n all these cobaltous salts, dpsL/dHc < O, at least when the external field Hc is lower than 1000 gauss. A second problem which will be reported, concerns paramagnetic relaxation in two ions system such as Co--Fe, Co--Ni and so on. If a certain a m o u n t of the cobaltous ions is replaced by ferrous ions, dpsr./dHc becomes positive and if replaced by nickelous fans, it remains negative, b u t b/C becomes large at large external field. Besides these cobaltous systems, the results of systems such as Co--Zn, C u - - F e , Cu--Ni, will be reported.
102. P a r a m a g n e t i c R e l a x a t i o n in N i c k e l FluosiHcate. W. B. MIMS and K. D. BOWERS. Bell Telephone Laboratories, Murray Hill (N.Y.) U.S.A. A pulsed microwave method has been used to investigate paramagnetic relaxation at liquid helium temperature in crystals of nickel fluosilicate magnetically diluted with zinc fluosilicate. ]Experiments were made without external quantising field, and at frequencies near 4 kilomegacycles corresponding to the zero field splitting. We have observed the build-up to a steady value of spin temperature when microwave power is applied and have followed the decay when power is removed; the decay deviates markedly from the exponential form required b y simple theory. Relaxation has been studied over a range of temperatures from 4.2°K to 1.8°K, and in crystals of different magnetic concentration. The immediate physical environment of the crystal was changed from helium hquid to helium gas without producing a n y appreciable effect on the relaxation time.
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occurs in a restricted range of magnetic fields; in this same range double relaxation effects are found (of. 8) 4)). All these anomalous effects show a marked crystalline anisotropy. I n the 1 : 40 diluted crystals the specific heat anomalies and double relaxations are absent. This m a y suggest t h a t they have to do with interactions between nearest neighbours. I n the silico fluoride crystals (1 : 0 and 1 : 10) no anomalous behaviour has been found. 1) 2) 3) 4)
Benzie, R..J., Cooke, A. H. and Whitley, S., Proc. roy Soc. 232 (1955) 277. Hascda, T. and Kanda, ]E., Physica 22 (1956) 647. Van der Marel, L. C., thesis Leiden 1958. See L. C. Van der Marel's abstract at this conference (No. 98).
101. Pararnagnetic R e l a x a t i o n in Cobaltous Salts at Liquid H e l i u m T e m p e r a tures. T. H A S E D A and E: KANDA.
The Research Institute for Iron, Steel and Other IVfetals, TShoku University, Sendal, Japan. We have measured paramagnetic relaxation in some cobaltous salts at liquid helium temperatures and found an anomaly in the field dependence of spin-lattic relaxation time such as dpsL/dHc < O. Salts examined, are CoNH4-Tutton, CoK-Tutton, COSO4.7H20, CoI2.9H~O, CoSiF8.6H20, etc. I n all these cobaltous salts, dpsL/dHc < O, at least when the external field Hc is lower than 1000 gauss. A second problem which will be reported, concerns paramagnetic relaxation in two ions system such as Co--Fe, Co--Ni and so on. If a certain a m o u n t of the cobaltous ions is replaced by ferrous ions, dpsr./dHc becomes positive and if replaced by nickelous fans, it remains negative, b u t b/C becomes large at large external field. Besides these cobaltous systems, the results of systems such as Co--Zn, C u - - F e , Cu--Ni, will be reported.
102. P a r a m a g n e t i c R e l a x a t i o n in N i c k e l FluosiHcate. W. B. MIMS and K. D. BOWERS. Bell Telephone Laboratories, Murray Hill (N.Y.) U.S.A. A pulsed microwave method has been used to investigate paramagnetic relaxation at liquid helium temperature in crystals of nickel fluosilicate magnetically diluted with zinc fluosilicate. ]Experiments were made without external quantising field, and at frequencies near 4 kilomegacycles corresponding to the zero field splitting. We have observed the build-up to a steady value of spin temperature when microwave power is applied and have followed the decay when power is removed; the decay deviates markedly from the exponential form required b y simple theory. Relaxation has been studied over a range of temperatures from 4.2°K to 1.8°K, and in crystals of different magnetic concentration. The immediate physical environment of the crystal was changed from helium hquid to helium gas without producing a n y appreciable effect on the relaxation time.