Relaxation Effects in Antiferromagnetic Resonance of CuCl 2 2H 2 O

Various relaxation times observed in antiferromagnetic resonance of CuCl 2 2H 2 O are investigated experimentally. Both pulsed and continuous high power microwaves of about 160 milli-watts were applied to the single crystal at low temperatures and the rise and decay times of the induced magnetization M z , shift of the resonance line, and complex susceptibilities χ' and χ'' were investigated in detail. Three characteristic relaxation times are specified. The transverse component M x , y decays with relaxation time T 2 of about 10 -8 sec while the longitudinal component M z relaxes with T 1 a of about 10 -7 sec. An empirical formula for T 1 a is obtained as T 1 a =(1.1±0.1)×10 -6 T -(5.0±0.5) which is considered as the spin-lattice relaxation time. Another relaxation time T 1 b of the order of 10 -3 ∼10 -5 sec is also observed and the origin of this relaxation is attributed to the lattice-bath heat transfer relaxation.

[1]  G. Shirane,et al.  Canted Antiferromagnetism of CuCl2·2D2O , 1967 .

[2]  M. Date,et al.  Antiferromagnetic Resonance Linewidth in CuF 2 2H 2 O , 1966 .

[3]  M. Date,et al.  New Antiferromagnetic Resonance Lines in CuCl22H2O , 1966 .

[4]  M. Date,et al.  Antiferromagnetic Relaxation in CuCl 2 2H 2 O , 1966 .

[5]  A. B. Harris.  Relaxation in Antiferromagnets due to Spin‐Wave Interactions , 1966 .

[6]  T. Kawasaki.  A Green Function Theory of Antiferromagnetic Relaxation , 1965 .

[7]  G. Shirane,et al.  Magnetic structure of CuCl2 · 2H2O , 1965 .

[8]  C. Naiman,et al.  Spin‐Flopping Relaxation Time in CuCl2·2H2O , 1965 .

[9]  R. Loudon,et al.  Effect of Dipolar Fields on the Antiferromagnetic Spin-Wave Spectrum , 1963 .

[10]  K. Tani.  Antiferromagnetic Spin Waves , 1963 .

[11]  K. Sinha,et al.  Phonon-Magnon interaction in magnetic crystals. II. Antiferromagnetic systems , 1963 .

[12]  M. Date,et al.  Antiferromagnetic Resonance in Hydrated Copper Salts , 1963 .

[13]  A. Heeger.  Spin-Wave Instability and Premature Saturation in Antiferromagnetic Resonance , 1963 .

[14]  T. Moriya.  Anisotropic Superexchange Interaction and Weak Ferromagnetism , 1960 .

[15]  A. H. Nethercot,et al.  Antiferromagnetic Resonance in MnF 2 , 1959 .

[16]  T. Moriya,et al.  On the Origin of the Anisotropy Energy of CuCl2-2H2O , 1953 .

[17]  S. A. Friedberg.  The specific heat of CuCl2·2H2O between 1.5 and 20°K , 1952 .

[18]  K. Tomita,et al.  GREEN'S FUNCTION THEORY OF MAGNETIC RELAXATION. III. THE CASE OF AN ALTERNANT MAGNET , 1965 .

[19]  H. Gerritsen,et al.  Antiferromagnetic resonance line widths in CuCl2.2H2O at 9400 MHz , 1956 .

[20]  C. Gorter,et al.  On the susceptibility of CuCl2.2H2O powder in the antiferromagnetic and paramagnetic states , 1955 .

[21]  N. Bloembergen,et al.  Relaxation Effects in Para- and Ferromagnetic Resonance , 1954 .

[22]  J. Ubbink.  Theory of anti-ferromagnetic resonance in a crystal of rhombic symmetry at the absolute zero , 1953 .

[23]  R. Damon.  Relaxation Effects in the Ferromagnetic Resonance , 1952 .