Properties of the zigzag spin chains with various nearest-neighbor and next-nearest-neighbor interactions are studied by making use of the transfer-matrix renormalization group method. Thermodynamic quantities of the systems (temperature dependence of the susceptibility and the specific heat), as well as the field dependence of the magnetization are analyzed numerically with a high accuracy in the thermodynamic limit. The results have been compared with the recent experimental data on Rb2Cu2Mo3O12.

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An unusual and rather large transient lateral photovoltage ͑LPV͒ has been observed in La 0.9 Sr 0.1 MnO 3 / SrNb 0.01 Ti 0.99 O 3 and La 0.7 Sr 0.3 MnO 3 / Si heterojunctions under the nonuniform irradiation of pulsed laser. The irreversible LPVs on both sides of a p-n junction challenge the well established model for LPV in conventional semiconductor p-n junctions, which can be well explained by the Dember effect. Much larger LPV is observed in La 0.7 Sr 0.3 MnO 3 / Si than that in La 0.9 Sr 0.1 MnO 3 / SrNb 0.01 Ti 0.99 O 3 . Similar results measured from both substrates of SrNb 0.01 Ti 0.99 O 3 and Si also support such a Dember effect. Much larger LPVs in heterojunctions than those in simple samples ͑SrNb 0.01 Ti 0.99 O 3 or Si͒ suggest a potential application of Dember effect in heterostructures.

Ultraviolet photoelectricity based on the vicinal cut as-supplied SrTiO3 single crystals has been experimentally studied in the absence of an applied bias at room temperature. An open-circuit photovoltage of 130ps rise time and 230ps full width at half maximum was observed under the irradiation of a 355nm pulsed laser of 25ps in duration. The dependence of the photoelectric effect on the tilting angles was studied, and the optimum angle is 20.9°. Seebeck effect is proposed to elucidate the tilting angle dependence of laser-induced photovoltage. This work demonstrates the potential of SrTiO3 single crystals in ultraviolet detection.

It was proposed that ionic liquids (IL) used as the gated dielectric in EDLT can form a strong electric fi eld at the interface between IL and oxides to electrostatically manipulate the high carrier density in a range of ≈10 14 -10 15 cm −2 , leading to the change of the electronic phase of transitional metal oxides, while it is not achievable via fi eld-effect transistor gated with conventional dielectric. [4][5][6][7][8][9][10][11][12][13][14][15][16] However, some recent reports argued that the mechanism of electronic phase change is the creation of oxygen vacancies caused by the electric fi eld in oxides, [17][18][19][20] instead of electrostatic carrier doping. On the other hand, some other results claimed that the change of the electronic phase in correlated oxides is the result of chemical doping via an electrochemical reaction. [21][22][23][24] Despite these great efforts that have been made, the underlying mechanism of IL gating driving MIT has been a matter of debate so far. Therefore, it is of vital importance to reveal the origin of the electrical control of MIT in transitional metal oxides using IL as gate mediums.The perovskite manganite materials are of signifi cant interest for those who wish to control and understand MIT in correlated oxides, as well as an excellent platform for exploring how the oxygen vacancies occur and what role they play in the electronic phase transition by electrolyte gating, because of the high correlation with the valence state of manganese determined by the oxygen stoichiometry. [ 2,25 ] In this work, we focus on a typical hole-doped perovskite oxide material, La 0.8 Sr 0.2 MnO 3 (LSMO), featured with colossal magnetoresistance and phase separation. [ 25 ] First, we will present the manipulation of the electronic phase transition by using IL gating, and the realization of a resistance increase of more than four orders of magnitude in the LSMO fi lms. Then it will be shown that the oxygen vacancies are responsible for MIT of LSMO fi lms. Finally from a series of comparative experiments presented in this work, we conclude that these oxygen vacancies are originated by the electrochemical reaction at the interface gated by IL electrolytes, and the amount of the trace water contained in the IL plays an indispensable role in the generation of oxygen vacancies in LSMO fi lms.The thin fi lms of LSMO were grown on single crystal (001) LaAlO 3 (LAO) substrates by pulsed laser deposition. The crosssectional high-angle annular dark-fi eld (HAADF) scanning transmission electron microscopy (STEM) image exhibits the LSMO/LAO sharp interface, indicating a high quality of the epitaxial heterostructure ( Figure S1, Supporting Information). It was patterned into a Hall-bar structure with coplanar In correlated transitional metal oxides, the coupling of charge, spin, orbital, and lattice degree of freedoms gives rise to the rich physics, including metal-insulator transition (MIT) [ 1 ] and interface related multifunctional properties. [ 2 ] The electric fi eld control of these intriguing p...

Epitaxial BiFeO3∕La0.7Sr0.3MnO3 (BFO/LSMO) heterostructures were grown on SrTiO3 (001) substrates. Dielectric properties of the BFO thin films were investigated in an In/BFO/LSMO capacitor configuration. The capacitance of the capacitor shows strong dependences on measuring frequency and bias voltage especially in low frequency region (⩽1MHz). By means of complex impedance analysis, it is found that the interfacial polarization caused by space charges in the film/electrode interfaces plays an important role in the dielectric behavior of the capacitor. Our results indicate that the influences of film/electrode interfaces might not be neglected on the dielectric properties of the BFO thin film capacitors.

Solar-blind deep-ultraviolet (DUV) photoconductive detectors based on an LaAlO(3) (LAO) single crystal with interdigitated electrodes are reported. The LAO detectors show a high sensitivity to DUV light with wavelengths less than 210 nm, and the DUV/UV (200 versus 290 nm) contrast ratio is more than 2 orders of magnitude. The photocurrent responsivity of LAO detector reaches 71.8 mA/W at 200 nm at 10 V bias, and the corresponding quantum efficiency eta is 44.6%. The noise current under sunlight at midday outdoors is only 77 pA. The experimental results indicate that the LAO detectors have attractive potential applications in DUV detection.

Epitaxially grown functional perovskites on silicon (001) and the ferroelectricity of a 3.2 nm thick BaTiO3 barrier layer are demonstrated. The polarization-switching-induced change in tunneling resistance is measured to be two orders of magnitude. The obtained results suggest the possibility of integrating ferroelectric tunnel junctions as binary data storage media in non-volatile memory cells on a silicon platform.