Comparison of the normal state properties of κ\kappa-(BEDT-TTF)2_2Cu(NCS)2_2 and its deuterated analogue in high magnetic fields and under high hydrostatic pressures

Details of the Fermi-surface topology of deuterated $\kappa$-(BEDT-TTF)$_2$Cu(NCS)$_2$ ~have been measured as a function of pressure, and compared with equivalent measurements of the undeuterated salt. We find that the superconducting transition temperature is much more dramatically suppressed by increasing pressure in the deuterated salt. It is suggested that this is linked to pressure-induced changes in the Fermi-surface topology, which occur more rapidly in the deuterated salt than in the undeuterated salt as the pressure is raised. Our data suggest that the negative isotope effect observed on deuteration is due to small differences in Fermi-surface topology caused by the isotopic substitution.Comment: 10 pages 3 figure

Giant Hysteretic Single‐Molecule Electric Polarisation Switching above Room Temperature

Continual progress has been achieved in information technology through unrelenting miniaturisation of the single memory bit in integrated ferromagnetic, ferroelectric, optical, and related circuits. However, as miniaturisation approaches its theoretical limit, new memory materials are being sought. Herein, we report a unique material exhibiting single‐molecule electric polarisation switching that can operate above room temperature. The phenomenon occurs in a Preyssler‐type polyoxometalate (POM) cluster we call a single‐molecule electret (SME). It exhibits all the characteristics of ferroelectricity but without long‐range dipole ordering. The SME affords bi‐stability as a result of the two potential positions of localisation of a Tb3+ ion trapped in the POM, resulting in extremely slow relaxation of the polarisation and electric hysteresis with high spontaneous polarisation and coercive electric fields. Our findings suggest that SMEs can potentially be applied to ultrahigh‐density memory and other molecular‐level electronic devices operating above room temperature.This study was supported by JSPS KAKENHI Grant Numbers JP16H04223, JP16K14101, JP24350095, and JP25220803;the Joint Research Project between JSPS and the National Science Foundation of China (NSFC);and JSPS Core-to-Core Program, A. Advanced Research Networks. This work was also performed under the aegis of the Canon Science Promotion Foundation, Murata Science Foundation, Casio Science Promotion Foundation, and the Cooperative Research Program of “Network Joint Research Centre for Materials and Devices”. M.K. is also funded by CNRS, France.アクセプト後にキーワード・アブストラクト等変更あり

Influence of reaction conditions on the channel shape of 3d-4f heterometallic metal-organic framework

Three structural kinds of 3d-4f metal-organic-frameworks (MOFs), {[Ln(4)(ox)(3)(Ni(IDA)(2))(3)(H2O)(6)]}(n)center dot xnH(2)O (Type I: Ln=La, Nd, Eu, Gd; IDA = iminodiacetate, ox = oxalate), {[Ln(2) (ox)(Ni(IDA) (2))(2)(H2O)(2)]}(n)center dot 2nH(2)O (Type II: Ln=La, Pr, Nd, Eu) and {[Dy-2(ox)(2)Ni(IDA)(2)(H2O)(2)]}(n)center dot 2nH(2)O (Type III), have been synthesized under hydrothermal condition. The crystal structures consist of Ln-oxalate tetramers for Type I, dimers for Type II and one-dimensional polymers for Type III bridged by the metalloligand [Ni(IDA)(2)](2-). While Type I contains a mixture of "Ln(6)Ni(4)-parallelogram" (A-Type) and "Ln(6)Ni(2)-parallelogram" (B-Type) channels, Type II and Type III contain only A-type and B-type channels, respectively. A fairly high stability of the MOFs is indicated by thermogravimetric analyses and reversible dehydration and rehydration of guest water molecules, which is confirmed by single crystal-to-single crystal transformation of 1 and 5.NNSFC [20471050, 20531050, 20721001]; MSTC [2007CB815304]; CNRS-Franc

Synthesis, structures and magnetic properties of dimeric copper and trimeric cobalt complexes supported by bridging cinnamate and chelating phenanthroline

International audienc