在高磁场下关闭Kondo绝缘体Ce3Bi4Pt3中的旋转间隙
1Los Alamos National Laboratory, New Mexico 87545, USA. mjaime@lanl.gov
Nature
|May 23, 2000
概括
康多绝缘体,如Ce3Bi4Pt3,随着温度下降,从金属过渡到绝缘. 强大的磁场诱导金属状态,证实了差距.
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
- 量子材料是一种量子材料.
背景情况:
- 康多绝缘体是金属间化合物,表现出温度依赖的金属绝缘体过渡.
- 这种过渡的特点是,在费米水平上开辟了一个能量差距,归因于传导带和f电子水平之间的杂交.
- 了解差距形成和关闭的机制对于探索新型电子性质至关重要.
研究的目的:
- 为了研究高磁场对Kondo绝缘体Ce3Bi4Pt3.3电子性能的影响.
- 通过实验验证Kondo绝缘体中拟议的差距关闭机制.
- 为了证明Ce3Bi4Pt3.3中的场诱导的绝缘体到金属的过渡.
主要方法:
- 在直流 (直流) 和脉冲磁场下,对Ce3Bi4Pt3进行了特定热量测量,高达60特斯拉.
- 数据分析涉及数值计算和考克布林-施里弗模型的应用.
- 与理论预测进行比较,以解释观察到的现象.
主要成果:
- 特定热量测量显示,在高磁场下,电子行为的显著变化.
- 数据明确表明,在Ce3Bi4Pt3.3中,场所诱导的过渡从绝缘状态到金属状态.
- 观察到的转变与Kondo引发的能源差距的缩小是一致的.
结论:
- 高磁场可以有效地弥合Kondo绝缘体中的能量差距,推动过渡到金属状态.
- 结果为Kondo绝缘体中混合动力驱动的差距模型提供了强有力的实验证据.
- Ce3Bi4Pt3是研究f电子系统中场诱导量子相变的关键材料.
更多相关视频
06:49Radio Frequency Magnetron Sputtering of GdBa2Cu3O7−δ/ La0.67Sr0.33MnO3 Quasi-bilayer Films on SrTiO3 (STO) Single-crystal Substrates
Published on: April 12, 2019
09:06Visualizing Uniaxial-strain Manipulation of Antiferromagnetic Domains in Fe1+YTe Using a Spin-polarized Scanning Tunneling Microscope
Published on: March 24, 2019
相关概念视频
02:42Valence 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...
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
01:14Atomic Nuclei: Nuclear Spin State Population Distribution
Near absolute zero temperatures, in the presence of a magnetic field, the majority of nuclei prefer the lower energy spin-up state to the higher energy spin-down state. As temperatures increase, the energy from thermal collisions distributes the spins more equally between the two states. The Boltzmann distribution equation gives the ratio of the number of spins predicted in the spin −½ (N−) and spin +½ (N+) states.
01:23Atomic Nuclei: Nuclear Relaxation Processes
In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin to precess and orient themselves along (lower energy) or against (higher energy) the direction of the field. At equilibrium, a slight excess population of spins exists in the lower energy state. Because the direction of the magnetic field is fixed as the z-axis, the precessing magnetic moments are randomly oriented around the z-axis. This...
01:31Ferromagnetism
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...
01:28Magnetostatic Boundary Conditions
An electric field suffers a discontinuity at a surface charge. Similarly, a magnetic field is discontinuous at a surface current. The perpendicular component of a magnetic field is continuous across the interface of two magnetic mediums. In contrast, its parallel component, perpendicular to the current, is discontinuous by the amount equal to the product of the vacuum permeability and the surface current. Like the scalar potential in electrostatics, the vector potential is also continuous...