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小木虫论坛-学术科研互动平台 » 材料区 » 材料综合 » 材料物理 » 零场冷却和场冷却的区别
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linda19918

银虫 (小有名气)

[求助] 零场冷却和场冷却的区别已有1人参与

许多实验都要进行场冷却和零场冷却，做这个的目的是什么？其原理又是什么？
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1楼2014-07-18 14:09:16
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橡胶人

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【答案】应助回帖

感谢参与，应助指数 +1
推荐一帖：http://muchong.com/html/200911/1674598.html
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2楼2014-07-18 15:27:49
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linda19918

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If a magnetic field is applied as the sample is cooled to the transition temperature, magnetization of the sample increases as described by the Curie law. Upon reaching Tc, the sample becomes a spin glass and further cooling results in little change in magnetization. This is referred to as the field-cooled magnetization.

When the external magnetic field is removed, the magnetization of the spin glass falls rapidly to a lower value known as the remanent magnetization.

Magnetization then decays slowly as it approaches zero (or some small fraction of the original value—this remains unknown). This decay is non-exponential and no simple function can fit the curve of magnetization versus time adequately.[1] This slow decay is particular to spin glasses. Experimental measurements on the order of days have shown continual changes above the noise level of instrumentation.[1]

Spin glasses differ from ferromagnetic materials by the fact that after the external magnetic field is removed from a ferromagnetic substance, the magnetization remains indefinitely at the remanent value. Paramagnetic materials differ from spin glasses by the fact that, after the external magnetic field is removed, the magnetization rapidly falls to zero, with no remanent magnetization. In each case the decay is rapid and exponential.[citation needed]

If the sample is cooled below Tc in the absence of an external magnetic field and a magnetic field is applied after the transition to the spin glass phase, there is a rapid initial increase to a value called the zero-field-cooled magnetization. A slow upward drift then occurs toward the field-cooled magnetization.

Surprisingly, the sum of the two complicated functions of time (the zero-field-cooled and remanent magnetizations) is a constant, namely the field-cooled value, and thus both share identical functional forms with time,[2] at least in the limit of very small external fields.
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3楼2014-07-18 17:48:21
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wbcui

至尊木虫 (知名作家)
看你要做什么材料了
有些材料的场冷-零场冷没有很大区别，也就是看出个距离温度吧，
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4楼2014-07-19 23:29:20
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yzc0616

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引用回帖:
3楼: Originally posted by linda19918 at 2014-07-18 17:48:21
If a magnetic field is applied as the sample is cooled to the transition temperature, magnetization of the sample increases as described by the Curie law. Upon reaching Tc, the sample becomes a spin  ...

ZFC/FC实验是，施加的磁场有什么要求吗？怎么确定加多大的磁场呢
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5楼2019-02-26 22:58:05
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