scholarly journals Terahertz pulse-driven collective mode in the nematic superconducting state of Ba1−xKxFe2As2

2022 ◽  
Vol 7 (1) ◽  
Author(s):  
Romain Grasset ◽  
Kota Katsumi ◽  
Pierre Massat ◽  
Hai-Hu Wen ◽  
Xian-Hui Chen ◽  
...  

AbstractWe investigate the collective mode response of the iron-based superconductor Ba1−xKxFe2As2 using intense terahertz (THz) light. In the superconducting state a THz Kerr signal is observed and assigned to nonlinear THz coupling to superconducting degrees of freedom. The polarization dependence of the THz Kerr signal is remarkably sensitive to the coexistence of a nematic order. In the absence of nematic order the C4 symmetric polarization dependence of the THz Kerr signal is consistent with a coupling to the Higgs amplitude mode of the superconducting condensate. In the coexisting nematic and superconducting state the signal becomes purely nematic with a vanishing C4 symmetric component, signaling the emergence of a superconducting collective mode activated by nematicity.

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Takeshi Suzuki ◽  
Takashi Someya ◽  
Takahiro Hashimoto ◽  
Shoya Michimae ◽  
Mari Watanabe ◽  
...  

Abstract Photoexcitation is a very powerful way to instantaneously drive a material into a novel quantum state without any fabrication, and variable ultrafast techniques have been developed to observe how electron, lattice, and spin degrees of freedom change. One of the most spectacular phenomena is photoinduced superconductivity, and it has been suggested in cuprates that the transition temperature Tc can be enhanced from the original Tc with significant lattice modulations. Here, we show a possibility for another photoinduced high-Tc superconducting state in the iron-based superconductor FeSe. The transient electronic state over the entire Brillouin zone is directly observed by time- and angle-resolved photoemission spectroscopy using extreme ultraviolet pulses obtained from high harmonic generation. Our results of dynamical behaviors from 50 fs to 800 ps consistently support the favourable superconducting state after photoexcitation well above Tc. This finding demonstrates that multiband iron-based superconductors emerge as an alternative candidate for photoinduced superconductors.


2019 ◽  
Vol 123 (6) ◽  
Author(s):  
H. Pfau ◽  
S. D. Chen ◽  
M. Yi ◽  
M. Hashimoto ◽  
C. R. Rotundu ◽  
...  

2012 ◽  
Vol 152 (8) ◽  
pp. 718-727 ◽  
Author(s):  
Hiroshi Kontani ◽  
Yoshio Inoue ◽  
Tetsuro Saito ◽  
Youichi Yamakawa ◽  
Seiichiro Onari

2002 ◽  
Vol 12 (9) ◽  
pp. 265-265
Author(s):  
V. Cvetkovic ◽  
J. Zaanen ◽  
Z. Nussinov

Biquadratic spin 1 Heisenberg spin systems can be constructed exhibiting spin nematic order in higher dimensions. In terms of the original spin degrees of freedom, the spontaneous nematic symmetry breaking generates a Z2 gauge invariance. Using a generalized Holstein-Primakoff transformation for the underlying U(3) dynamical algebra, we calculate the spin dynamical form factor. Although spin is not a gauge singlet, we find form factor to be finite at finite q and $$\backslash$omega$\backslash$$, contrary to our expectations regarding the presence of a energy scale protecting the gauge invariance. This result appears to be perturbatively stable.


2017 ◽  
Vol 7 (1) ◽  
Author(s):  
S. Arumugam ◽  
C. Ganguli ◽  
R. Thiyagarajan ◽  
D. Bhoi ◽  
G. Kalai Selvan ◽  
...  

2014 ◽  
Vol 10 (2) ◽  
pp. 97-104 ◽  
Author(s):  
R. M. Fernandes ◽  
A. V. Chubukov ◽  
J. Schmalian

2016 ◽  
Vol 93 (10) ◽  
Author(s):  
Yan Zheng ◽  
Pok Man Tam ◽  
Jianqiang Hou ◽  
Anna E. Böhmer ◽  
Thomas Wolf ◽  
...  

2002 ◽  
Vol 80 (1) ◽  
pp. 1-24 ◽  
Author(s):  
RJ Dwayne Miller

Biological molecules are mesoscopic systems that bridge the quantum and classical worlds. At the single molecule level, there are often more than 1 × 104 degrees of freedom that are involved in protein-mediated processes. These molecules are sufficiently large that the bath coordinate convolved to the reaction at an active site is defined by the surrounding protein tertiary structure. In this context, the very interatomic forces that determine the active protein structures create a strongly associated system. Thus, the bath fluctuations leading to reactive crossings involve highly hindered motions within a myriad of local minima that would act to cast the reaction dynamics into the high viscosity limit appropriate to glasses. However, the time scales observed for biological events are orders of magnitude too fast to meet this anticipated categorization. In this context, the apparent deterministic nature of biological processes represents an enormous challenge to our understanding of chemical processes. Somehow Nature has discovered a molecular scaffolding that enables minute amounts of energy to be efficiently channeled to perform biological functions without becoming entrapped in local minima. Clearly, energy derived from chemical processes is highly directed in biological systems. To understand this problem, we must first understand how energy is redistributed among the different degrees of freedom and fully characterize the protein relaxation processes along representative reaction coordinates in relation to these dissipative processes. This paper discusses the development of new nonlinear spectroscopic methods that have enabled interferometric sensitivity to protein motions on femtosecond time scales appropriate to the very fastest motions (i.e., bond breaking or the molecular "Big Bang") out to the slowest relaxation steps. This work has led to the Collective Mode Coupling Model as an explanation of the required reduced dimensionality in biological systems. Within this model, the largest coupling coefficients of the reaction coordinate are to the damped inertial collective modes of the protein defined by the strongly correlated secondary structures. These modes act to guide the reaction along the correct seam(s) in an otherwise highly complex potential energy surface. The mechanism by which biological molecules have been able to harness chemical energy over meso-length scales represents the first step towards higher levels of organization. The new insight afforded by the collective mode mechanism may prove important in understanding this larger issue of scaling in biological systems.Key words: biodynamics, energy transduction, ultrafast spectroscopy, nonlinear spectroscopy, primary processes in biology.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ying Xiang ◽  
Qing Li ◽  
Yongkai Li ◽  
Wei Xie ◽  
Huan Yang ◽  
...  

AbstractIn transition metal compounds, due to the interplay of charge, spin, lattice and orbital degrees of freedom, many intertwined orders exist with close energies. One of the commonly observed states is the so-called nematic electron state, which breaks the in-plane rotational symmetry. This nematic state appears in cuprates, iron-based superconductor, etc. Nematicity may coexist, affect, cooperate or compete with other orders. Here we show the anisotropic in-plane electronic state and superconductivity in a recently discovered kagome metal CsV3Sb5 by measuring c-axis resistivity with the in-plane rotation of magnetic field. We observe a twofold symmetry of superconductivity in the superconducting state and a unique in-plane nematic electronic state in normal state when rotating the in-plane magnetic field. Interestingly these two orders are orthogonal to each other in terms of the field direction of the minimum resistivity. Our results shed new light in understanding non-trivial physical properties of CsV3Sb5.


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