Spin diffusion and spin echoes in liquid 3He at low temperature
Spin diffusion and spin echoes in liquid 3He at low temperature
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低温液体 3He 中的自旋扩散和自旋回波
DOI：
10.1088/0022-3719/3/2/027
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发表时间：
1970
期刊：
影响因子：
--
通讯作者：
A. Leggett
中科院分区：
文献类型：
--
作者：
A. Leggett
研究了简并费米液体中的自旋扩散，考虑了准粒子之间相互作用产生的‘分子场’的影响。结果表明，即使在水动力极限条件下，一般也不存在常规形式的方程：m/t=Dgrad2M；真正的方程是非线性的，并且取决于相互作用的强度。因此，当lambda Omega 0 tau D>；约为1，其中Omega 0是Larmor频率，tau D是自旋扩散寿命，lambda是测量分子场强度的无量纲参数时，可以预测出实质性的新效应。具体地说，据预测，在‘Phi-180-180’实验中，自旋回波衰减一般不是指数的，而是依赖于外场和初始脉冲角Phi。对于纯~3He和混合~3He，新的效应都应该位于实验可及区域。
Spin diffusion in a degenerate Fermi liquid is studied, taking into account the effects of the 'molecular field' resulting from the interactions between quasiparticles. It is shown that even in the hydrodynamic limit no equation of the conventional form delta M/ delta t=Dgrad2M exists in general; the true equation is nonlinear and depends on the strength of the interactions. Substantial new effects are therefore predicted when lambda Omega 0 tau D> approximately 1, where Omega 0 is the Larmor frequency, tau D the spin diffusion lifetime and lambda a dimensionless parameter which measures the strength of the molecular field. Specifically, it is predicted that the spin-echo attenuation in a ' phi -180-180' experiment will in general not be exponential and will depend on the external field and the initial pulse angle phi . The new effects should lie in the experimentally accessible region both for pure 3He and for mixtures.