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Determine the chirality of Weyl fermions from the circular dichroism spectra of time-dependent ARPES  [PDF]
Rui Yu,Hongming Weng,Zhong Fang,Hong Ding,Xi Dai
Physics , 2015,
Abstract: We show that the intensity of pumped states near Weyl point is different when pumped with left- and right-handed circular polarized light, which leads to a special circular dichroism (CD) in time-dependent angle resolved photoemission spectra (ARPES). We derive the expression for the CD of time-dependent ARPES, which is directly related to the chirality of Weyl fermions. Based on the above derivation, we further propose a method to determine the chirality for a given Weyl point from the CD of time-dependent ARPES. The corresponding CD spectra for TaAs has then been calculated from the first principle, which can be compared with the future experiments.
Circular dichroism of cholesteric polymers and the orbital angular momentum of light  [PDF]
W. L?ffler,D. J. Broer,J. P. Woerdman
Physics , 2011, DOI: 10.1103/PhysRevA.83.065801
Abstract: We explore experimentally if the light's orbital angular momentum (OAM) interacts with chiral nematic polymer films. Specifically, we measure the circular dichroism of such a material using light beams with different OAM. We investigate the case of strongly focussed, non-paraxial light beams, where the spatial and polarization degrees of freedom are coupled. Within the experimental accuracy, we cannot find any influence of the OAM on the circular dichroism of the cholesteric polymer.
Common Origin of the Circular-dichroism Pattern in ARPES of SrTiO3 and CuxBi2Se3  [PDF]
Y. Ishida,H. Kanto,A. Kikkawa,Y. Taguchi,Y. Ito,Y. Ota,K. Okazaki,W. Malaeb,M. Mulazzi,M. Okawa,S. Watanabe,C. -T. Chen,M. Kim,C. Bell,Y. Kozuka,H. Y. Hwang,Y. Tokura,S. Shin
Physics , 2011, DOI: 10.1103/PhysRevLett.107.077601
Abstract: Circular dichroism in the angular distribution (CDAD) of photoelectrons from SrTiO3:Nb and CuxBi2Se3 is investigated by 7-eV laser ARPES. In addition to the well-known node that occurs in CDAD when the incidence plane matches the mirror plane of the crystal, we show that another type of node occurs when the mirror plane of the crystal is vertical to the incidence plane and the electronic state is two dimensional. The flower-shaped CDAD's occurring around the Fermi level of SrTiO3:Nb and around the Dirac point of CuxBi2Se3 are explained on equal footings. We point out that the penetration depth of the topological states of CuxBi2Se3 depends on momentum.
Concerning two-gap ARPES data, the pseudogap, 2-q striping and magnetc circular dichroism from the negative-U HTSC perspective  [PDF]
John A Wilson
Physics , 2007,
Abstract: Recent photoemission work on underdoped cuprates between Tc and T*, the pseudogap temperature, are interpreted within the framework of a previously developed negative-U scenario. From this exposition, incorporating a developed 2q diagonal striping model, detailed understanding follows of the ARPES results, together with certain STM and far infrared optical data. Identification of the origin of the magnetic circular dichroism and related effects exhibited by such materials below T* also appears to have been achieved.
Emergence of Orbital Angular Momentum by Inversion Symmetry Breaking and Its Detection by ARPES  [PDF]
Choong H. Kim,Jin-Hong Park,Jun Won Rhim,Beom Young Kim,Jaejun Yu,Masashi Arita,Kenya Shimada,Hirofumi Namatame,Masaki Taniguchi,Changyoung Kim,Jung Hoon Han
Physics , 2011,
Abstract: Rashba-split surface band is characterized by a one-to-one correspondence between the electron's momentum k and its spin orientation. Here we show that a similar correspondence between momentum and orbital angular momentum (OAM) must exist on surface bands once the inversion symmetry is broken. The correspondence is valid even when there is no spin-orbit interaction. Tight-binding and first-principles calculations are presented to support our claim. As a method to detect such OAM-momentum correspondence, we propose the circular dichroism (CD) experiment using the angle-resolved photoemission (ARPES) setup. CD-ARPES experiment performed on Cu surface confirms the existence of chiral OAM. A new concept of "orbital Galvanic effect" is proposed.
Angular momentum-induced circular dichroism in non-chiral nanostructures  [PDF]
Xavier Zambrana-Puyalto,Xavier Vidal,Gabriel Molina-Terriza
Physics , 2014, DOI: 10.1038/ncomms5922
Abstract: Circular dichroism (CD), i.e. the differential response of a system to left and right circularly polarized light, is one of the only techniques capable of providing morphological information of certain samples. In biology, for instance, CD spectroscopy is widely used to study the structure of proteins. More recently, it has also been used to characterize metamaterials and plasmonic structures. Typically, CD can only be observed in chiral objects. Here, we present experimental results showing that a non-chiral sample such as a sub-wavelength circular nano-aperture can produce giant CD when a vortex beam is used to excite it. These measurements can be understood by studying the symmetries of the sample and the total angular momentum that vortex beams carry. Our results show that CD can provide a wealth of information about the sample when combined with the control of the total angular momentum of the input field.
Observation of warping effects in the band and angular momentum structures of topological insulator Bi2Te3  [PDF]
Wonsig Jung,Yeongkwan Kim,Beomyoung Kim,Yoonyoung Koh,Chul Kim,Masaharu Matsunami,Shin-ichi Kimura,Masashi Arita,Kenya Shimada,Jung Hoon Han,Juyoung Kim,Beongki Cho,Changyoung Kim
Physics , 2011, DOI: 10.1103/PhysRevB.84.245435
Abstract: We performed angle resolved photoemission (ARPES) experiments on Bi2Te3 with circularly polarized light. ARPES data show very strong circular dichroism, indicating existence of orbital angular momentum (OAM). Moreover, the alignment of OAM is found to have a strong binding energy dependence. Such energy dependence comes from a relatively strong band warping effect in Bi2Te3 compared to Bi2Se3. OAM close to Dirac point has an ideal chiral structure (sin ?) without out-of-plane component. Warping effect comes in as the binding energy decreases and circular dichroism along a constant energy contour can no longer be explained by a simple sin? function but requires a sin3? term. When the warping effect becomes even stronger near the Fermi energy, circular dichroism gains an additional sin6? term. Such behavior is found to be compatible with the theoretically predicted OAM structure.
High orbital angular momentum quantum numbers in the electronic ground states of Fe$_2^+$ and Co$_2^+$ as determined by x-ray absorption and x-ray magnetic circular dichroism spectroscopy  [PDF]
V. Zamudio-Bayer,K. Hirsch,A. Langenberg,A. Lawicki,A. Terasaki,B. v. Issendorff,J. T. Lau
Physics , 2015,
Abstract: The $^6\Delta$ electronic ground state of the Co$_2^+$ diatomic molecular cation has been assigned experimentally by x-ray absorption and x-ray magnetic circular dichroism spectroscopy in a cryogenic ion trap. Three candidates, $^6\Phi$, $^6\Gamma$, and $^8\Gamma$, for the electronic ground state of Fe$_2^+$ have been identified. These states carry sizable ground-state orbital angular momenta that disagree with theoretical predictions from multireference configuration interaction and density functional theory. Our results show that the ground states of neutral and cationic diatomic molecules of $3d$ elements cannot be assumed to be connected by a one-electron process.
Detecting orbital angular momentum through division-of-amplitude interference with a circular plasmonic lens  [PDF]
Ai-Ping Liu,Xiao Xiong,Xi-Feng Ren,Yong-Jing Cai,Guang-Hao Rui,Qi-Wen Zhan,Guang-Can Guo,Guo-Ping Guo
Physics , 2013, DOI: 10.1038/srep02402
Abstract: We demonstrate a novel detection scheme for the orbital angular momentum (OAM) of light using circular plasmonic lens. Owing to a division-of-amplitude interference phenomenon between the surface plasmon waves and directly transmitted light, specific intensity distributions are formed near the plasmonic lens surface under different OAM excitations. Due to different phase behaviors of the evanescent surface plasmon wave and the direct transmission, interference patterns rotate as the observation plane moves away from the lens surface. The rotation direction is a direct measure of the sign of OAM, while the amount of rotation is linked to the absolute value of the OAM. This OAM detection scheme is validated experimentally and numerically. Analytical expressions are derived to provide insights and explanations of this detection scheme. This work forms the basis for the realization of a compact and integrated OAM detection architect that may significantly benefit optical information processing with OAM states.
Second-harmonic generation circular dichroism spectroscopy from tripod-like chiral molecular films

Wang Xiao-Ou,Chen Li-An,Chen Li-Xue,Sun Xiu-Dong,Li Jun-Qing,Li Chun-Fei,

中国物理 B , 2010,
Abstract: The second-harmonic generation (SHG) circular dichroism in the light of reflection from chiral films of tripod-like chiral molecules is investigated. The expressions of the second-harmonic generation circular dichroism are derived from our presented three-coupled-oscillator model for the tripod-like chiral molecules. Spectral dependence of the circular dichroism of SHG from film surface composed of tripod-like chiral molecules is simulated numerically and analysed. Influence of chiral parameters on the second-harmonic generation circular dichroism spectrum in chiral films is studied. The result shows that the second-harmonic generation circular dichroism is a sensitive method of detecting chirality compared with the ordinary circular dichroism in linear optics. All of our work indicates that the classical molecular models are very effective to explain the second-harmonic generation circular dichroism of chiral molecular system. The classical molecular model theory can give us a clear physical picture and brings us very instructive information about the link between the molecular configuration and the nonlinear processes.
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