纯金属的偏磁阶段中的铁液分解
N Doiron-Leyraud1, I R Walker, L Taillefer
1Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK. nd223@cam.ac.uk
Nature
|October 10, 2003
概括
研究人员发现,费米液态模型,一种金属标准理论,在3D金属MnSi中意外地分解. 这种异常发生在磁过渡附近,挑战现有的量子临界点理论.
科学领域:
- 凝聚物质物理学 凝聚物质物理学
- 材料科学 材料科学 材料科学
- 量子关键的现象 量子关键的现象
背景情况:
- 费米液体理论是描述金属行为的标准模型.
- 在量子临界点附近观察到异常的金属特性,挑战了费米液体理论.
- 在量子临界点附近的不寻常行为在理论上超出了标准模型的预测.
研究的目的:
- 在3D金属MnSi中调查费米液体理论的分解.
- 探索在磁过渡附近异常金属行为的性质.
- 为了确定观察到的异常是否与量子关键交叉现象一致.
主要方法:
- 在MnSi.上进行电阻测量.
- 测量是在各种压力,温度和应用磁场的范围内进行的.
- 分析了电阻的温度依赖性,以确定偏离费米流体行为的偏差.
主要成果:
- 在MnSi中观察到Fermi-液体模型的意想不到的崩在一个广泛的相位图区域.
- 这种分解发生在一级磁性过渡附近,而不是量子临界点.
- 观察到的电阻的异常温度依赖性与典型的量子临界交叉行为不一致.
结论:
- 这些发现挑战了对费米液体理论局限性的传统理解.
- 在MnSi的异常行为接近一阶磁性过渡表明了超越标准模型的新物理学.
- 这可能表明物质出现了一个新的量子相.
相关概念视频
Bonding in Metals
Metallic bonds are formed between two metal atoms. A simplified model to describe metallic bonding has been developed by Paul Drüde called the “Electron Sea Model”.
Valence Bond Theory
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
Diamagnetism
Materials consisting of paired electrons have zero net magnetic moments. However, when these materials are placed under an external magnetic field, the moments opposite to the field are induced. Such materials are called diamagnets. Diamagnetism is the response of the diamagnets when placed in an external magnetic field.
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets.
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets.
Ferromagnetism
Materials like iron, nickel, and cobalt consist of magnetic domains, within which the magnetic dipoles are arranged parallel to each other. The magnetic dipoles are rigidly aligned in the same direction within a domain by quantum mechanical coupling among the atoms. This coupling is so strong that even thermal agitation at room temperature cannot break it. The result is that each domain has a net dipole moment. However, some materials have weaker coupling, and are ferromagnetic at lower...
Paramagnetism
Paramagnets are materials with unpaired electrons that possess a finite magnetic moment. In the absence of a magnetic field, these moments are randomly oriented, and thus the net moment is zero. Under an external field, a torque acting on the moments tends to align them along the field's direction. However, the random thermal motion of electrons produces a torque opposite to the external field and tries to disorient the moments. These two competing effects align only a few moments along the...
Magnetic Susceptibility and Permeability
In linear magnetic materials, like paramagnets and diamagnets, magnetization is proportional to the magnetic field intensity. The constant of proportionality, a dimensionless number, is called magnetic susceptibility. The value of the susceptibility depends on the type of material.
When diamagnetic materials are placed under an external magnetic field, the moments opposite to the field are induced. Hence, the susceptibility for diamagnets has a minimal negative value of 10-5–10-6. Since...
When diamagnetic materials are placed under an external magnetic field, the moments opposite to the field are induced. Hence, the susceptibility for diamagnets has a minimal negative value of 10-5–10-6. Since...


