Electron spin-lattice relaxation measurements in a two-dimensional crystal

The spin relaxation times T1 and T2 are studied in a two-dimensional magnetic system by varying the angle between the anisotropy axis and the external magnetic field. Measurements are done on the Mn2+ ions in a single crystal of (C2H5NH3)2MnCl4, using the new technique of longitudinal detection of electron spin resonance (LODESR). The angular dependence of T1 is explained by taking into account an isotropic interaction besides the exchange modulated dipolar interaction. The theoretical curves are in fair agreement with experiments. Le temps de relaxation T1 and T2 des spins, ont ete etudiees, dans un systeme magnetique a deux dimensions, en function de l'angle entre l'axe de anisotropie et le champ magnetique statique. Les mesures ont ete effectuees sur les ions de Mn2+ dans un monocristal de (C2H5NH3)2MnCl4, avec une nouvelle technique de detection longitudinelle de la resonance paramagnetique electronique. La dependance angulaire de T1 a ete interpretee avec l'assumption de deux mecanismes: une interaction dipolaire modulee par l'echange et une interaction isotrope. Les resultats theoriques sont en bon accord avec les mesures effectuees.

[1]  S. Santucci,et al.  Electron-spin double resonance by longitudinal detection. II. Signal dependence on relaxation times , 1977 .

[2]  S. Santucci,et al.  Electron-spin double resonance by longitudinal detection: Line shape and many-quantum transitions , 1975 .

[3]  S. Santucci,et al.  Dependence on relaxation times of longitudinally detected paramagnetic resonance , 1975 .

[4]  P. M. Richards,et al.  Exchange narrowing of electron spin resonance in a two-dimensional system , 1974 .

[5]  F. Waldner,et al.  New phase transition in (CnH2n+1NH3)2MnCl4 , 1973 .

[6]  D. Huber.  Critical-Point Anomalies in the Electron-Paramagnetic-Resonance Linewidth and in the Zero-Field Relaxation Time of Antiferromagnets , 1972 .

[7]  L. J. Jongh,et al.  Magnetic measurements on (CH3NH3)2MnCl4, a quasi two-dimensional Heisenberg antiferromagnet , 1972 .

[8]  P. Bloembergen,et al.  Transition temperatures of weakly anisotropic layer-type magnets. Dependence on anisotropy , 1972 .

[9]  R. Willett,et al.  Crystal Structure of (CH3CH2CH2NH3)2MnCl4 , 1972 .

[10]  M. F. Collins,et al.  Neutron scattering from paramagnets , 1967 .

[11]  K. Kawasaki.  Anomalous spin relaxation near the magnetic transition , 1967 .

[12]  Leo P. Kadanoff,et al.  Hydrodynamic equations and correlation functions , 1963 .

[13]  H. Carr,et al.  The Principles of Nuclear Magnetism , 1961 .

[14]  R. Kubo,et al.  A General Theory Of Magnetic Resonance Absorption , 1954 .

[15]  P. Anderson,et al.  Exchange Narrowing in Paramagnetic Resonance , 1953 .