顺磁性物质中法拉第磁光效应及其温度特性的量子理论

在某些顺磁性物质中,包括交换作用和外磁场在内的有效场H_i可导致基态能级的分裂。在温度T高于居里点T_c范围内,基态分裂的两个能级上均可存在一定的电子几率分布,从而可导致基态双能级跃迁。根据这一理论进行的计算表明,顺磁性物质的法拉第效应存在多种温度特性。在外磁场不太大的情况下,有些物质的费尔德常数V与磁化率X的比值V/X=A(1+BT);有些物质中V/X=A(1+B/T)。计算还表明,法拉第旋转的实部θ′和虚部θ″均与有效场H_i成正比,并在非吸 关键词：     

顺磁性物质CeF3中磁化率和费尔德常数的定量计算

本文首先计及晶场对顺磁性物质CeF_3中Ce~(3+)离子4f基态和5d激发态能级的影响,进而考虑了间接交换作用有效场II_v和外磁场H_e共同作用下导致的晶场基态能级的进一步分裂,然后应用基态双能级跃迁模型定量计算了CeF_3中的比法拉第旋转θ_F,费尔德常数F和磁化率X以及它们与温度的依赖关系.计算表明,CeF_3中的磁光效应及其温度特性与Ce~(3+)离子之间的间接交换作用密切相关,在60相似文献   

对称强双色共振场中弛豫效应对二能级系统斯塔克分裂的影响

本文应用半径典理论、密度矩阵方法和探索场中二能级系统的能级斯塔克(Stark)分裂。指出与无弛豫效应相比较,弛予效应不仅改变了由光学斯塔克效应所产生的分裂能级的权重、展宽了这些能级,而且还出现新的分裂能级。     

顺磁物质CeF_3磁光Faraday效应及其温度特性的量子理论

本文计算了顺磁物质CeF, 因Ce离子从基态能级4 f 至s d 的电偶极跃迁产生的F a r a d a y 旋转. 讨论晶场对Ce 离子4 f 和s d 能级的影响, 通过唯象地引入一个与磁化强度M成正比的“附加磁场”H=M,由此获得4 t 离子在外加磁场和“ 附加磁场” 的共同作用下的一级Ze e m a n 分裂. 经劈裂后的两个子能级上各自产生左、右圆偏振光激发的电偶极跃迁, 导致磁光F a r a d a y 效应.对于波长为0.6 3 2 8 微米 的人射光, 在60 一如OK 温度范围内计算得到的ver det 常数和磁化率能够较好地与实验相符. 关键词：     

本征GaAs中电子自旋极化的能量演化研究

采用时间分辨圆偏振光抽运-探测光谱,研究9.6 K温度下本征GaAs中电子自旋相干弛豫动力学,发现反映电子自旋相干的吸收量子拍的振幅随光子能量的增加呈非单调性变化.考虑自旋极化依赖的带填充效应和带隙重整化效应,发展了圆偏振光抽运-探测光谱的理论模型.该模型表明量子拍的振幅依赖于所探测能级的电子初始自旋极化度,自旋探测灵敏度以及带填充因子,三者的乘积导致了量子拍振幅的非单调变化,与实验结果一致.给出了能级分裂的二能级系统中电子自旋极化度定义.发现在高能级上可以获得100%的初始电子自旋极化度. 关键词： 圆偏振光抽运-探测光谱 吸收量子拍 电子自旋极化度 GaAs     

溶胶-凝胶法制备ZnO薄膜及其光致发光性质

利用溶胶-凝胶法在石英衬底上制备了ZnO薄膜,通过测量样品的透射谱、X射线衍射谱、扫描电子显微镜(SEM)图像和光致发光谱研究了其结构特征和发光性质.结果表明:在衍射角2θ=34.32°处出现了对应(002)晶面的强衍射峰,ZnO膜呈多晶状态,具有六角纤矿晶体结构和良好的C轴择优取向,薄膜中颗粒的平均粒径为56nm;光致发光呈多发光峰状,有中心波长为378nm的紫带,520nm绿带,446nm附近的蓝带以及发现未见报道过的绿带以后中心波长为586nm和570nm两个弱发射峰.实验结果表明,制备的ZnO薄膜具有发光特性,但内部与深能级发射相关的结构缺陷浓度还是较高,样品中两个低能量光致发光应来源于晶粒间界的缺陷能级,多缺陷能级导致了多发射峰的光致发光谱.     

V型三能级系统中五阶极化拍频的理论研究

从理论上研究了由于五阶极化强度间的干涉所导致的Ｖ型三能级系统相闰共轭超快调制光谱学，考虑了抽运光束为窄带线宽或宽带线宽的情形。发现能级分裂的测量精度决定于光学跃迁的均匀增宽，即这种技术在测量能级分裂时可得到消除多普勒增宽的精度。     

射频驱动下电磁诱导透明窗口的分裂和增益的出现

在Λ型三能级系统的基础上引入两个共振射频场, 通过详细讨论系统的探测吸收特性随两个射频场Rabi频率取不同值时的变化规律, 得出电磁诱导透明(EIT)的分裂规律以及EIT上出现增益现象的产生条件.研究结果表明: 两个射频场对系统所起的控制作用不同, 控制基态精细结构能级之间跃迁的射频场对EIT的分裂起作用, 而控制激发态精细结构能级之间跃迁的射频场不会导致EIT的分裂; 而且, 只有当控制基态精细结构能级之间跃迁的射频场的Rabi频率大于控制激发态精细结构能级之间跃迁的射频场的Rabi频率时, 才能产生EIT与增益相叠加的新特性. 关键词： 射频场 电磁诱导透明 增益 精细结构能级     

磁光Kerr效应的温度特性研究

从磁光Kerr效应的微观量子表述出发，分别研究了铁磁材料和亚铁磁材料的磁光Kerr效应的温度特性。结果表明，磁光Kerr转角θK与材料磁化强度随温度变化关系不同。铁磁材料θK对磁化强度M的级数展开式中仅含M奇次项。亚铁磁材料可以出现磁化强度M≠0而磁光Kerr转角θK=0情况。     

红宝石吸收光谱中锐线能级与分裂计算

本文采用LГ表象,考虑到不同组态间的相互作用(立方场,三角场与自旋轨道作用),计算了红宝石中锐线B,S与R线的能级及其分裂和基态的分裂。所得结果是B线与R线跟实验较符合,基态的分裂较实验值小,这可能是更高能级的三角场与自旋轨道的微扰作用所引起的。 关键词：     

Four-Level Transition Analysis of the Polar Kerr Effects in Ferrornagnetics

In ferromagnetics, besides originating from the splitting of the excited state resulting from the spin-orbit interaction, magneto-op tical effects also stem from the splitting of the ground state caused by the exchange interaction and the applied field. Theoretical calculation according to this view shows that, in ferromagnetics, there are electron transitions corresponding to two pairs of left- and right-handed circularly polarized lights, and the polar Kerr rotation θ_κ depends linearly on magnetization M in both regions of low temperature and high temperature for the material with high Curie temperature T_c. When considering the different oscillator strengths in normal temperature region between the above two regions, we obtain the expressions of θ_κ as forms similar to θ_κ ≅∑_n=0α(M/T)ⁿ and θ_κ≅∑_n=0βM^n+l/Tⁿ.     

The measurement of frequency dependance of surface resistance in high Tc superconductor

We have measured the penetration depth and conductivity of high Tc superconductor at liquid nitrogen temperature by using microwave transmission method. After that we obtain the frequency dependance of surface resistance in high Tc superconductor. Experimental results show that the surface resistance of high Tc superconductor is proportional to the square of frequency as theoretical prediction. The advantage of microwave transmission method is broadband and easy to use.     

Cr掺杂对BaxSr1-xRuO3体系磁性和输运性质的影响

本文采用固相反应法制备了BaxSr1-xRuO3和BaxSr1-xRu0.9Cr0.1O3两组样品,对比研究了它们磁性和电输运性质.当掺杂量少于0.2时,体系处于有少许畸变的钙钛矿的3C结构,Cr的掺入很大幅度提高了体系的铁磁转变温度Tc,电输运性质上也由坏金属行为转变为Mott绝缘体的行为,并且在铁磁相变附近出现电阻拐点.当掺杂量大于等于0.2时,体系发生结构相变,由畸变钙钛矿3C结构变为6 M的单斜结构.这时,Cr的掺入对体系的影响并不明显.这些结果表明引起SrRuO3铁磁转变温度升高的Ru+5-O-Cr+3相互作用对晶格结构有强烈的依赖关系.     

Field-enhanced diamagnetism in the pseudogap state of the cuprate Bi2Sr2CaCu2O(8+delta) superconductor in an intense magnetic field

In hole-doped cuprates, Nernst experiments imply that the superconducting state is destroyed by spontaneous creation of vortices which destroy phase coherence. Using torque magnetometry on Bi2Sr2CaCu2O(8+delta), we uncover a field-enhanced diamagnetic signal M above the transition temperature Tc that increases with applied field to 32 Tesla and scales just like the Nernst signal. The magnetization results above Tc distinguish M from conventional amplitude fluctuations and strongly support the vortex scenario for the loss of phase coherence at Tc.     

Spin-orbit coupled Fermi gases across a Feshbach resonance

In this Letter we study both ground state properties and the superfluid transition temperature of a spin-1/2 Fermi gas across a Feshbach resonance with a synthetic spin-orbit coupling, using the mean-field theory and the exact solution of two-body problem. We show that a strong spin-orbit coupling can significantly enhance the pairing gap for negative scattering length a(s), due to increased density of state at Fermi surface. Strong spin-orbit coupling can also significantly enhance the superfluid transition temperature Tc to a sizable fraction of Fermi temperature when a(s) ≤ 0, while it suppresses Tc slightly for positive a(s). The interaction energy and pair size at resonance are also discussed.     

Mössbauer study on M1 and M2 sites of Fe2+ in natural hypersthene under dynamic crystal field potential approach

⁵⁷Fe Mössbauer spectra of hypersthene, a natural silicate mineral belonging to the orthopyroxene group, have been taken over the temperature range 77–292 K. At temperatures above 77 K, they show asymmetric quadrupole peaks. This asymmetry arises from the overlapping of two quadrupole doublets from Fe²⁺(3d⁶,⁵D) ions in two different sites (M1 and M2). The quadrupole splitting, isomer shift and their temperature dependence are appreciably different for Fe²⁺ ions in the two sites. The Fe²⁺ quadrupole splitting in the M1 site decreases linearly with temperature, which can be explained quite satisfactorily by using a very simple model of the orbit-lattice interaction.     

Study of highT c superconductivity in Y1Ba2Cu3O7−x by PAC

HighT _c superconductivity in the YBaCuO superconductor has been investigated through the quadrupole interaction of the probe nuclei⁹⁹Tc. The quadrupole interactions were measured by the TDPAC method from 77 to 296 K. The probe nuclei⁹⁹Tc were introduced into the YBaCuO superconducting specimen by diffusion. The derived electric quadrupole interaction parameters show that the probe nuclei are subject to a unique EFG interaction and occupy a substitutional lattice site in the YBaCuO superconductor. A strong EFG of 10¹⁹ V/cm² was observed. The temperature dependence of the EFG exhibits a linear decrease with temperature increase. Anomalies of both EFG and ν were found in the superconducting transition temperature region. The role of the oxygen vacancies in the Cu−O chains is discussed.     

激光诱导的钛酸钡等离子体的时间分辨光谱

利用光学多通道分析仪（ＯＭＡⅢ）研究脉冲激光沉积钛酸钡薄膜过程中的激光诱导等离子体的时间分辨发射光谱，利用各种粒子不同时刻发射的谱线强度描绘成该粒子的飞行时间谱，表征了等离子体中该粒子的空间浓度分布，根据飞行时间谱的特征，推算了粒子束脉冲（等离子体）的空间宽度及其与缓冲气体压力的关系，提出了在激光沉积多元氧化物薄膜过程中的合适的缓冲气体压力范围，解释了激光原位沉积高温超导薄膜中所需氧气分压达３０Ｐ