scholarly journals Charge Order Breaks Magnetic Symmetry in Molecular Quantum Spin Chains

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
M. Dressel ◽  
M. Dumm ◽  
T. Knoblauch ◽  
B. Köhler ◽  
B. Salameh ◽  
...  
Keyword(s):  
Domain Walls ◽  
Interaction Mechanism ◽  
Charge Order ◽  
Magnetic Interaction ◽  
Quantum Spin ◽  
Quantum Spin Chains ◽  
Molecular Plane ◽  
Spin Resonance ◽  
Spin Arrangement ◽  
Magnetic Symmetry

Charge order affects most of the electronic properties but is believed not to alter the spin arrangement since the magnetic susceptibility remains unchanged. We present electron-spin-resonance experiments on quasi-one-dimensional(TMTTF)2Xsalts (X=PF6, AsF6, and SbF6), which reveal that the magnetic properties are modified belowTCOwhen electronic ferroelectricity sets in. The coupling of anions and organic molecules rotates the g-tensor out of the molecular plane creating magnetically nonequivalent sites on neighboring chains at domain walls. Due to anisotropic Zeeman interaction a novel magnetic interaction mechanism in the charge-ordered state is observed as a doubling of the rotational periodicity ofΔH.

scholarly journals Charge-Order Phase Transition in the Quasi One-Dimensional Organic Conductor $${\hbox {(TMTTF)}}_2 {\hbox {NO}}_3$$

2020 ◽  
Vol 51 (11) ◽  
pp. 1321-1329
Author(s):  
Lena Nadine Majer ◽  
Björn Miksch ◽  
Guilherme Gorgen Lesseux ◽  
Gabriele Untereiner ◽  
Martin Dressel
Keyword(s):  
Charge Order ◽  
Relaxation Processes ◽  
Organic Conductor ◽  
One Dimensional ◽  
Spin Resonance ◽  
Ordered Phases ◽  
Spin Arrangement ◽  
Low Dimensional ◽  
A Charge ◽  
Pm 10

AbstractLow-dimensional organic conductors show a rich phase diagram, which has, despite all efforts, still some unexplored regions. Charge ordered phases present in many compounds of the $${\hbox {(TMTTF)}}_2X$$ (TMTTF) 2 X family are typically studied with their unique electronic properties in mind. An influence on the spin arrangement is, however, not expected at first glance. Here, we report temperature and angle dependent electron spin resonance (ESR) measurements on the quasi one-dimensional organic conductor $${\hbox {(TMTTF)}}_2 {\hbox {NO}}_3$$ (TMTTF) 2 NO 3 . We found that the $${\hbox {(TMTTF)}}_2 {\hbox {NO}}_3$$ (TMTTF) 2 NO 3 compound develops a peculiar anisotropy with a doubled periodicity ($$ab'$$ a b ′ -plane) of the ESR linewidth below about $$T_{\text {CO}}= ({250\pm 10})~\hbox {K}$$ T CO = ( 250 ± 10 ) K . This behavior is similar to observations in the related compounds $${\hbox {(TMTTF)}}_2X$$ (TMTTF) 2 X ($$X = {\hbox {PF}}_6$$ X = PF 6 , $${\hbox {SbF}}_6$$ SbF 6 and $${\hbox {AsF}}_6$$ AsF 6 ), where it has been attributed to relaxation processes of magnetically inequivalent sites in the charge-ordered state. For the structural analogous $${\hbox {(TMTTF)}}_2 {\hbox {ClO}}_4$$ (TMTTF) 2 ClO 4 , known for the absence of charge order, such angular dependence of the ESR signal is not observed. Therefore, our ESR measurements lead us to conclude that a charge-order phase is stabilized in the title compound below $$T_{\text {CO}} \approx 250~\hbox {K}$$ T CO ≈ 250 K .

scholarly journals Confinement and Entanglement Dynamics on a Digital Quantum Computer

2020 ◽  
Author(s):  
Joseph Vovrosh ◽  
Johannes Knolle
Keyword(s):  
Bound States ◽  
Domain Walls ◽  
Quantum Computer ◽  
Entanglement Entropy ◽  
Transverse Field ◽  
Quantum Spin ◽  
Spin Chains ◽  
Quantum Computers ◽  
Quantum Spin Chains ◽  
Quantum Phenomena

Abstract Confinement describes the phenomenon when the attraction between two particles grows with their distance, most prominently found in quantum chromodynamics (QCD) between quarks. In condensed matter physics, confinement can appear in quantum spin chains, for example, in the one dimensional transverse field Ising model (TFIM) with an additional longitudinal field, famously observed in the quantum material cobalt niobate or in optical lattices. Here, we establish that state-of-the-art quantum computers have reached quantum simulation capabilities to explore confinement physics in spin chains. We report quantitative confinement signatures of the TFIM on an IBM quantum computer observed via two distinct velocities for information propagation from domain walls and their mesonic bound states. We also find the confinement induced slow down of entanglement spreading by implementing randomized measurement protocols for the second order Renyi entanglement entropy. Our results are a crucial step for probing non-perturbative interacting quantum phenomena on digital quantum computers beyond the capabilities of classical hardware.

scholarly journals Confinement and entanglement dynamics on a digital quantum computer

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Joseph Vovrosh ◽  
Johannes Knolle
Keyword(s):  
Bound States ◽  
Domain Walls ◽  
Quantum Computer ◽  
Entanglement Entropy ◽  
Transverse Field ◽  
Quantum Spin ◽  
Spin Chains ◽  
Quantum Computers ◽  
Quantum Spin Chains ◽  
Quantum Phenomena

AbstractConfinement describes the phenomenon when the attraction between two particles grows with their distance, most prominently found in quantum chromodynamics (QCD) between quarks. In condensed matter physics, confinement can appear in quantum spin chains, for example, in the one dimensional transverse field Ising model (TFIM) with an additional longitudinal field, famously observed in the quantum material cobalt niobate or in optical lattices. Here, we establish that state-of-the-art quantum computers have reached capabilities to simulate confinement physics in spin chains. We report quantitative confinement signatures of the TFIM on an IBM quantum computer observed via two distinct velocities for information propagation from domain walls and their mesonic bound states. We also find the confinement induced slow down of entanglement spreading by implementing randomized measurement protocols for the second order Rényi entanglement entropy. Our results are a crucial step for probing non-perturbative interacting quantum phenomena on digital quantum computers beyond the capabilities of classical hardware.

Solvable nineteen-vertex models and quantum spin chains of spin one

1994 ◽  
Vol 4 (8) ◽  
pp. 1151-1159 ◽  
Author(s):  
Makoto Idzumi ◽  
Tetsuji Tokihiro ◽  
Masao Arai
Keyword(s):  
Quantum Spin ◽  
Spin Chains ◽  
Quantum Spin Chains ◽  
Vertex Models
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