Uniaxial pressure or strain can introduce a symmetry-breaking distortion on the lattice and may alter the ground states of a material. Compared to hydrostatic pressure, a unique feature of the uniaxial-pressure measur...Uniaxial pressure or strain can introduce a symmetry-breaking distortion on the lattice and may alter the ground states of a material. Compared to hydrostatic pressure, a unique feature of the uniaxial-pressure measurements is that a tensile force can be applied and thus a “negative” pressure can be achieved. In doing so, both ends of the sample are usually glued on the frame of the uniaxial-pressure device. The maximum force that can be applied onto the sample is sometimes limited by the shear strength of the glue, the quality of the interface between the sample and the glue, etc. Here we use focused ion beam to reduce the width of the middle part of the sample, which can significantly increase the effective pressure applied on the sample. By applying this technique to a home-made piezobender-based uniaxial-pressure device, we can easily increase the effective pressure by one or two orders of magnitude as shown by the change of the superconducting transition temperature of an iron-based superconductor. Our method thus provides a possible way to increase the upper limit of the pressure for the uniaxial-pressure devices.展开更多
Recent studies on the kagome lattice YCu_(3)(OH)_(6+x)X_(3-x)(X=Cl,Br)have provided promising evidence for the existence of Dirac quantum spin liquids.In this study,we synthesized a new compound,LuCu_(3)(OH)_(6)Br_(2)...Recent studies on the kagome lattice YCu_(3)(OH)_(6+x)X_(3-x)(X=Cl,Br)have provided promising evidence for the existence of Dirac quantum spin liquids.In this study,we synthesized a new compound,LuCu_(3)(OH)_(6)Br_(2)[Br_(x)(OH)_(1-x)],which has two types of structures with two different space groups,P3m1 and R3.The type-Ⅰ sample with a space group of P3m1 had undistorted Cu^(2+)kagome planes and orders magnetically below approximately 1.5 K.The type-Ⅱ sample had a larger unit cell with a space group of R3 and distorted kagome planes.No magnetic ordering was observed,and the low-temperature specific heat behaved like a Dirac quantum spin liquid,including a quadratic temperature dependence at zero field and an additional linear𝑇term under magnetic fields.By comparing the structures with those of YCu_(3)(OH)_(6+x)X_(3-x)(X=Cl,Br),we show that the quantum spin liquid ground state may have a deep connection with the𝐽J■-J-J′Heisenberg model in the kagome lattice.展开更多
基金Project supported by the National Key Research and Development Program of China (Grant Nos. 2022YFA1403402,2021YFA1400401, 2020YFA0406003, and 2017YFA0302903)the National Natural Science Foundation of China (Grant Nos. 11961160699 and 11874401)the Chinese Academy of Sciences (Grant Nos. XDB33000000 and GJTD-2020-01)。
文摘Uniaxial pressure or strain can introduce a symmetry-breaking distortion on the lattice and may alter the ground states of a material. Compared to hydrostatic pressure, a unique feature of the uniaxial-pressure measurements is that a tensile force can be applied and thus a “negative” pressure can be achieved. In doing so, both ends of the sample are usually glued on the frame of the uniaxial-pressure device. The maximum force that can be applied onto the sample is sometimes limited by the shear strength of the glue, the quality of the interface between the sample and the glue, etc. Here we use focused ion beam to reduce the width of the middle part of the sample, which can significantly increase the effective pressure applied on the sample. By applying this technique to a home-made piezobender-based uniaxial-pressure device, we can easily increase the effective pressure by one or two orders of magnitude as shown by the change of the superconducting transition temperature of an iron-based superconductor. Our method thus provides a possible way to increase the upper limit of the pressure for the uniaxial-pressure devices.
基金supported by the National Key Research and Development Program of China(Grant Nos.2022YFA1403400 and 2021YFA1400400)Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant Nos.XDB33000000 and GJTD-2020-01)。
文摘Recent studies on the kagome lattice YCu_(3)(OH)_(6+x)X_(3-x)(X=Cl,Br)have provided promising evidence for the existence of Dirac quantum spin liquids.In this study,we synthesized a new compound,LuCu_(3)(OH)_(6)Br_(2)[Br_(x)(OH)_(1-x)],which has two types of structures with two different space groups,P3m1 and R3.The type-Ⅰ sample with a space group of P3m1 had undistorted Cu^(2+)kagome planes and orders magnetically below approximately 1.5 K.The type-Ⅱ sample had a larger unit cell with a space group of R3 and distorted kagome planes.No magnetic ordering was observed,and the low-temperature specific heat behaved like a Dirac quantum spin liquid,including a quadratic temperature dependence at zero field and an additional linear𝑇term under magnetic fields.By comparing the structures with those of YCu_(3)(OH)_(6+x)X_(3-x)(X=Cl,Br),we show that the quantum spin liquid ground state may have a deep connection with the𝐽J■-J-J′Heisenberg model in the kagome lattice.
