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Light-Induced Current Oscillations in the Charge-Ordered State of (TMTTF)2SbF6
摘要： Below TCO = 157 K the quasi-one-dimensional charge-transfer salt (TMTTF)2SbF6 undergoes a pronounced phase transition to a charge-ordered ground state. We have explored the non-linear and photoconductive behavior as a function of applied voltage, laser pulse energy and temperature. Besides a decay of the photoconductive signal in a double exponential fashion in the millisecond range, we discover current oscillations in the kHz range induced by the application of short laser pulses. While the resonance frequencies do not depend on voltage or laser intensity and vary only slightly with temperature, the amplitude changes linearly with the laser intensity and voltage. We suggest that photo-induced fluctuations of the charge-ordered state alter the current flow of the single particles and hence, the photocurrent. The findings are discussed and compared to comparable phenomena in other low-dimensional electron systems.
关键词： TMTTF,non-linear transport,calculations of band structure and optical conductivity,charge-transfer salts,photoconductivity,current oscillations,charge-order phase transition
更新于2025-09-11 14:12:44
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Temperature-driven phase transitions and enhanced piezoelectric responses in Ba(Ti0.92Sn0.08)O3 lead-free ceramic
摘要： Ferroelectric phases coexistence or transition is an important strategy on generating high piezoelectricity. Here, the temperature-induced phase structural evolution correlated with small signal piezoelectric response d33, bias-field piezoelectric activity dmax33 (E), unipolar and bipolar strain piezoelectric outputs d*33 in Ba(Ti0.92Sn0.08)O3 (BTS0.08) ceramic was investigated in details. Temperature-driven successive phase transitions from rhombohedral(R) to orthorhombic(O), tetragonal(T), finally to cubic(C) phases took place around 14 °C, 38 °C and 61 °C, respectively. The highest d33 value of 675 pC/N is achieved in the T-C phase transition. However, the O-T phase boundary gives the highest dmax33 = 1170 pm/V, bipolar d*33 = 822 pm/V and unipolar d*33 = 1318 pm/V. The temperature-driven phase transition exhibits large enhancements in piezoelectric property comparable to that of composition-induced phase boundary. These features suggest an effective method to design high-performance piezoelectrics by tailoring the types of phase boundary.
关键词： Phase transition,Lead-free piezoceramics,Ferroelectrics,Phase boundary
更新于2025-09-10 09:29:36
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The effects of terbium oxide on phase transition and electronic properties of potassium-sodium niobate-based ceramics
摘要： Lead free piezoelectric ceramics 0.96K0.48Na0.52Nb0.96Sb0.04O3-0.04Bi0.5(Na0.82K0.18)0.5ZrO3-xmol%Tb4O7 (KNNS- BNKZ-xTb4O7) are prepared by solid state reaction method. The effects of Tb4O7 on phase transition, grain growth and electronic properties of the ceramics are studied. Tb4O7 (x (cid:1) 0.2) induces a phase transition from tetragonal-orthorhombic coexistence phases to pseudo-cubic one. Meanwhile, Tb4O7 could reduce grain size and lead to step-like grain growth. In addition, Tb4O7 could enhance the temperature stability of KNNS-BNKZ ceramics. For pure KNNS-BNKZ ceramics, the d33* and kp are reduced by 68.0% and 24.3%, respectively, from 30 (cid:3)C to 150 (cid:3)C. For the component x ? 0.1, they are reduced by 6.1% and 1.6%, respectively, in the same temperature range. This paper may have positive signi?cance for searching lead free piezoelectric ceramics with excellent temperature stable properties.
关键词： Piezoelectric ceramics,Phase transition,Lead free,Temperature stability
更新于2025-09-10 09:29:36
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A single layered organic-inorganic hybrid compound [(FBMA)2PbBr4] with reversible phase transition and intense fluorescent property
摘要： Reactions of 3-fluoro-N-methylbenzylamine (FBMA) with PbBr2 in concentrated HBr aqueous solution afforded a two-dimensional (2D) single layered organic-inorganic hybrid material [(FBMA)2PbBr4], which was confirmed by X-ray single crystal diffraction, infrared (IR) spectroscopy and powder X-ray diffraction (PXRD). The thermodynamic DSC analysis revealed it has a pair of reversible phase transition peaks with large thermal hysteresis exhibiting a first-order type phase transition. The variable-temperature single crystal diffraction proved the phase transition is originated from the order and disorder of organic-inorganic hybrid structures at room and high temperatures. Simultaneously compound [(FBMA)2PbBr4] exhibited a strong emission peak at 443 nm when under an excitation wavelength of 380 nm.
关键词： 2D single layered compound,fluorescent property,reversible phase transition,Organic-inorganic hybrid
更新于2025-09-10 09:29:36
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Magnetic field-induced electronic phase transition in the Dirac semimetal state of black phosphorus under pressure
摘要： Different instabilities have been confirmed to exist in the three-dimensional (3D) electron gas when it is confined to the lowest Landau level in the extreme quantum limit. The recently discovered 3D topological semimetals offer a good platform to explore these phenomena due to the small sizes of their Fermi pockets, which means the quantum limit can be achieved at relatively low magnetic fields. In this work, we report the high-magnetic-field transport properties of the Dirac semimetal state in pressurized black phosphorus. Under applied hydrostatic pressure, the band structure of black phosphorus goes through an insulator-semimetal transition. In the high pressure topological semimetal phase, anomalous behaviors are observed on both magnetoresistance and Hall resistivity beyond the relatively low quantum limit field, which is demonstrated to indicate the emergence of an exotic electronic state hosting a density wave ordering. Our findings bring the first insight into the electronic interactions in black phosphorus under intense field.
关键词： High magnetic field,Electron phase transition,Quantum limit,Black phosphorus
更新于2025-09-10 09:29:36
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Dynamic imaging of small molecule-induced protein-protein interactions in living cells with a fluorophore phase transition-based approach
摘要： Protein-protein interactions (PPIs) mediate signal transduction in cells. Small molecules that regulate PPIs are important tools for biology and biomedicine. Dynamic imaging of small molecule-induced PPIs characterizes and verifies these molecules in living cells. It is thus important to develop cellular assays for dynamic visualization of small molecule-induced protein-protein association and dissociation in living cells. Here we have applied fluorophore phase transition-based principle and designed a PPI assay named SPPIER (separation of phases-based protein interaction reporter). SPPIER utilizes the green fluorescent protein (GFP) and is thus genetically encoded. Upon small molecule-induced PPI, SPPIER rapidly forms highly fluorescent GFP droplets in living cells. SPPIER detects immunomodulatory drugs (IMiDs)-induced PPI between cereblon and the transcription factor Ikaros. It also detects IMiDs analog (e.g. CC-885)-induced PPI between cereblon and GSPT1. SPPIER can be modified to image small molecule-induced protein-protein dissociation, such as nutlin-induced dissociation between HDM2 and p53. The intensive brightness and rapid kinetics of SPPIER enable robust and dynamic visualization of PPIs in living cells.
关键词： GFP,Small molecules,SPPIER,Living cells,Fluorophore phase transition,Protein-protein interactions
更新于2025-09-10 09:29:36
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Nonlinear Dicke Quantum Phase Transition and Its Quantum Witness in a Cavity-Bose–Einstein-Condensate System
摘要： We investigate nonlinear Dicke quantum phase transition (QPT) induced by inter-atomic nonlinear interaction and its quantum witness in a cavity-Bose–Einstein-condensate (BEC) system. It is shown that inter-atomic nonlinear interaction in a cavity BEC system can induce first-order Dicke QPT. It is found that this nonlinear Dicke QPT can happen in an arbitrary coupling regime of the cavity and atoms. It is demonstrated that the quantum speed limit time can witness the Dicke QPT through its sudden change at the critical point of the QPT.
关键词： quantum speed limit time,cavity-Bose–Einstein-condensate system,nonlinear Dicke quantum phase transition
更新于2025-09-10 09:29:36
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz2018) - Nagoya, Japan (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Spectroscopy of Temperature-Driven Single Valley Dirac Fermions in HgTe/CdHgTe Quantum Wells
摘要： We report on the temperature-dependent magneto-absorption and magnetotransport spectroscopy of HgTe/CdHgTe quantum wells above the critical well thickness dc. Our results, obtained in magnetic fields up to 16 T and temperature range from 1.7 to 150 K, clearly indicate a change in the band-gap energy with temperature. A topological phase transition between quantum spin Hall and trivial insulator states, revealing appearance of single-valley Dirac fermions at T = 27 and 90 K for 6.5 and 8 nm QWs respectively, was clearly observed in our magnetospectroscopy measurements.
关键词： magneto-absorption,topological phase transition,Dirac fermions,HgTe/CdHgTe quantum wells,magnetotransport spectroscopy
更新于2025-09-10 09:29:36
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Visualization of a Berezinskii–Kosterlitz–Thouless Topological Phase Transition in a Josephson Medium: Detection of an Anomalous Temperature Dependence of the Magnetoresistance of YBa2Cu3O7–δ Granular High-Temperature Superconductors
摘要： The possibility of implementing a Berezinskii–Kosterlitz–Thouless topological phase transition in a Josephson medium of two-level high-temperature superconductors induced by a magnetic field has been studied. The effect of temperature and external magnetic field on the transport properties of the YBa2Cu3O7 – δ granular high-temperature superconductor considered as a model object is studied experimentally. For the first time, an anomalous behavior of the magnetoresistance isotherms is detected in a narrow range of temperature and external magnetic field indicating a topological phase transition in the Josephson medium of granular high-temperature superconductors.
关键词： YBa2Cu3O7 – δ,high-temperature superconductors,magnetoresistance,Josephson medium,Berezinskii–Kosterlitz–Thouless topological phase transition
更新于2025-09-10 09:29:36
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Estimation of the Temperature of the Current Filament that Forms upon Switching in GeSbTe
摘要： The current–voltage characteristics of thin-film samples of the GeSbTe system are measured in the current control mode. Voltage oscillations observed after switching are investigated. It is shown that these oscillations can be associated with the formation of a hot current filament and its gradual cooling. The size and temperatures of the current filament are estimated. It is shown that the characteristic temperature in the hot current filament corresponds to the temperature of the phase transition to the crystalline state.
关键词： phase transition,GeSbTe,voltage oscillations,switching effect,current filament
更新于2025-09-10 09:29:36