Effects of phonons and nuclear spins on the tunneling of a domain wall

被引:15
作者
Dube, M
Stamp, PCE
机构
[1] Univ British Columbia, Dept Phys & Astron, Vancouver, BC V6T 1Z1, Canada
[2] Univ British Columbia, Canadian Inst Adv Res, Vancouver, BC V6T 1Z1, Canada
[3] Univ Helsinki, Helsinki Inst Phys, FIN-00014 Helsinki, Finland
[4] Aalto Univ, Phys Lab, FIN-02150 Espoo, Finland
关键词
D O I
10.1023/A:1022676810365
中图分类号
O59 [应用物理学];
学科分类号
摘要
We consider the quantum dynamics of a magnetic domain wall at low temperatures, where dissipative couplings to magnons and electrons are very small, The wall motion is then determined by its, coupling to phonons and nuclear-spins, and any pinning potentials. In the absence of nuclear spins there is a dominant super Ohmic 1-phonon coupling to the wall velocity, plus a strongly T-dependent Ohmic coupling to pairs of phonons, There is also a T-independent Ohmic coupling between single phonons and the wall chirality, which suppresses "chirality tunneling". We calculate the effect of these couplings on the T-dependent tunneling rate of a wall out of a pinning potential. Nuclear spins have a very strong and hitherto unsuspected influence on domain, wall dynamics, coming from a hyperfine-mediated coupling to the domain wall position, For k(B)T much greater than omega(0) this coupling yields a spatially random potential, fluctuating at a late governed by the nuclear T-2. When k(B)T <much less than omega(0), the hyperfine potential fluctuates around a linear binding potential, The wall dynamics is influenced by the fluctuations of this potential, ie., by the nuclear spin dynamics. Wall tunneling can occur when fluctuations open an occasional "tunneling window". This changes the crossover to tunneling and also causes a slow "wandering", in time, of the energy levels associated with domain wall motion inside the pinning potential, This effect is fairly weak in Ni-and Fe-based magnets, and we give an approximate treatment of its effect on the tunneling dynamics, as well as a discussion of the relationship to recent domain wall tunneling experiments.
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页码:779 / 840
页数:62
相关论文
共 133 条
[1]   Effect of the magnetic environment on the tunneling of a giant spin [J].
Abarenkova, N ;
dAuriac, JCA .
PHYSICS LETTERS A, 1996, 219 (5-6) :335-344
[2]   MAGNETOSTATIC ENERGY OF THE SOLITON IN A CYLINDER [J].
AHARONI, A .
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, 1995, 140 :1819-1820
[3]  
ANDREEV AF, 1969, ZH EKSP TEOR FIZ, V29, P1107
[4]  
Auerbach A., 1994, INTERACTING ELECT QU
[5]   MACROSCOPIC QUANTUM TUNNELING IN MAGNETIC PROTEINS [J].
AWSCHALOM, DD ;
SMYTH, JF ;
GRINSTEIN, G ;
DIVINCENZO, DP ;
LOSS, D .
PHYSICAL REVIEW LETTERS, 1992, 68 (20) :3092-3095
[6]   MACROSCOPIC QUANTUM EFFECTS IN NANOMETER-SCALE MAGNETS [J].
AWSCHALOM, DD ;
DIVINCENZO, DP ;
SMYTH, JF .
SCIENCE, 1992, 258 (5081) :414-421
[7]  
AWSCHALOM DD, 1993, PHYS REV LETT, P2199
[8]  
AWSCHALOM DD, 1993, PHYS REV LETT, P4276
[9]  
AWSCHALOM DD, 1996, SCIENCE, P425
[10]   INSTANTONS IN SUPERFLUID HE-3 [J].
BAILIN, D ;
LOVE, A .
JOURNAL OF PHYSICS A-MATHEMATICAL AND GENERAL, 1980, 13 (08) :L271-L277