1991 Fiscal Year Final Research Report Summary
Study on Fluctuation and Relaxation near zero Kelvin.
| Project/Area Number |
02804018
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
物性一般（含極低温･固体物性に対する理論）
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| Research Institution | Kyoto Univetsity |
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Principal Investigator |
HIRAI Akira Kyoto University, Department of Physics, Associate Professor., 理学部, 助教授 (70025287)
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| Co-Investigator(Kenkyū-buntansha) |
SASAKI Yutaka Kyoto Univ., Dept. of Chemistry, Research Technician, 理学部, 教務技官 (60205870)
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| Project Period (FY) |
1990 – 1991
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| Keywords | Ultralow Temperatures / Fluctuation / Relaxation / l / f Noise / GaAs Semiconductor Devices / High Temperature Superconducting Films / u2d2 Phase of Solid ^3 He. |
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| Research Abstract |
According the the third law of the equilibrium thermodynamics(Nernst theorem), the entropy of any system goes to zero, when the temperature of the system approaches to absolute zero Kelvin. Is there any general rule about the fluctuation or the relaxation near the absolute zero Kelvin ? It was the purpose of the present study to get some hints about the above question by studying experimentally the relaxation and fluctuation(noise)near the absolute zero Kelvin.
As to therelaxation phenomena at ultralow temperatures, we have studied the relaxation of the uniform mode of the antiferromagnetic resonance in the u2d2 phase of the solid 3He. For a small excitation from the equilibrium condition, relaxation phenomena can be well described by a multi-magnon processes following the standard theory of the irreversible statistical mechanics. However, for larger excitations at low temperatures dynamical instability of the motion of spin system play important role. Spin dynamics of superfluid 3He at ultralow temperatures, where the number of quasiparticles are few, similar instability is very important in determining the "relaxation" phenomena.
AS the the noise measurements, in addition to that on the GaAs semiconductor devices, we have measured the voltage noise power spectrum from "high temperature superconducting thin films". It was found that from good samples we could not observe any excess 1/f noise and concluded that the noise is generated at the twin boundaries. A simple model is presented which accounts for the observed excess 1/f noise.
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