Raman and Other Optical Studies of Insulating Parent Phases of High Temperature Superconductors

高温超导体绝缘母相的拉曼和其他光学研究

• 批准号: 9320892
• 负责人: Miles Klein
• 金额: $ 24万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-04-15 至 1998-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9320892&HistoricalAwards=false
• 关键词: Raman; Other; Optical; Studies; Insulating

9320892 Klein Technical abstract: Cuprate superconductors evolve from a strongly-correlated state which has one carrier per active site and which is an antiferromagnetic insulator. When carriers are added via doping, correlation effects are believed to cause high temperature superconductivity. Photons can excite carrier pairs - one doubly-occupied copper site plus one empty site - or a carrier from a copper orbital to another orbital on the same site. These excitations are produced by photon absorption, Raman scattering, or as the intermediate state of a spin-exchange Raman process. To better understand their behavior the excitations are probed as functions of temperature, doping and magnetic field. Non-technical abstract: High temperature superconductors owe their properties to strong repulsive interactions among the carriers of electric current. They move among copper atoms, and when each copper atom has precisely one carrier, repulsion causes the carriers to become localized on the copper sites. Electrical conduction then ceases; the material is an insulator. In order to move the carriers a finite "quantum" of energy has to be supplied. This is done via adsorption of light or by means of scattered light. The properties of the excited carriers is studied as functions of temperature, doping and magnetic field. The goal is to understand the insulating phase in detail and thereby better understand the superconducting state that results from it. ***

9320892 Klein 技术摘要：铜酸盐超导体从强相关态演化而来，每个活性位点有一个载流子，并且是一种反铁磁绝缘体。 当通过掺杂添加载流子时，相关效应被认为会导致高温超导性。 光子可以激发载流子对（一个双占据铜位点加一个空位点）或将载流子从铜轨道激发到同一位点上的另一个轨道。 这些激发是由光子吸收、拉曼散射或作为自旋交换拉曼过程的中间态产生的。 为了更好地理解它们的行为，将激励作为温度、掺杂和磁场的函数进行探测。 非技术摘要：高温超导体的特性归因于电流载体之间的强排斥相互作用。 它们在铜原子之间移动，当每个铜原子恰好有一个载流子时，排斥力会导致载流子集中在铜位点上。 然后导电停止；该材料是绝缘体。 为了移动载流子，必须提供有限“量子”的能量。 这是通过吸收光或通过散射光来完成的。 研究了受激载流子的特性作为温度、掺杂和磁场的函数。 目标是详细了解绝缘相，从而更好地了解由此产生的超导状态。 ***