The recently discovered metal-intercalated iron selenide superconductors A2Fe4Se5 （A=K, Cs, T1- K, Rb, T1-Rb） （245） compounds, with Tc ～30K, have attracted much interest A high transition- temperature （TN ≈ 470...The recently discovered metal-intercalated iron selenide superconductors A2Fe4Se5 （A=K, Cs, T1- K, Rb, T1-Rb） （245） compounds, with Tc ～30K, have attracted much interest A high transition- temperature （TN ≈ 470-560K） and large magnetic moment （3.3μB/Fe） block antiferromagnetic （AFM） order exists in the superconducting samples. Mag- netic order-parameter experiences an anomaly when Tc is approached. The superconductors crystal- lize with a highly ordered √5 × √5 superstructure, in which the Fel site of the I4/m structure is only a few percents occupied and the Fe2 site is fully occupied. The non-superconducting samples at low-T also crystallize in the I4/m structure, while both Fe sites are fractionally occupied, since the numbers of the Fe vacancies in the samples and the vacant sites in the √5 × √5 pattern are mismatched. The partially ordered √5× √5 vacancy order becomes one of three competing phases for temperature below room temperature up to ～ 500K, namely, these sam- ples are phase-separated and in the miscibility gap 1lacier the n,mhi^nt condition.展开更多
Van der Waals magnet VI_(3) demonstrates intriguing magnetic properties that render it great for use in various applications.However,its microscopic magnetic structure has not been determined yet.Here,we report neutro...Van der Waals magnet VI_(3) demonstrates intriguing magnetic properties that render it great for use in various applications.However,its microscopic magnetic structure has not been determined yet.Here,we report neutron diffraction and susceptibility measurements in VI_(3) that revealed a ferromagnetic order with the moment direction tilted from the c-axis by ~36° at 4 K.A spin reorientation accompanied by a structure distortion within the honeycomb plane is observed,before the magnetic order completely disappears at TC=50 K.The refined magnetic moment of ~1.3μB at 4 K is much lower than the fully ordered spin moment of 2μB/V^(3+),suggesting the presence of a considerable orbital moment antiparallel to the spin moment and strong spin-orbit coupling in VI_(3).This results in strong magnetoelastic interactions that make the magnetic properties of VI_(3) easily tunable via strain and pressure.展开更多
基金Supported by the National Basic Research Program of China under Grant Nos 2012CB921700, 2011CBA00112, 2011CBA00103 and 2012CB821404, the National Natural Science Foundation of China under Grant Nos 11034012, 11190024, 11374261 and 11204059, the Natural Science Foundation of Zhejiang Province under Grant No LQI2A04007, and the Scientific User Facilities Division of the Office of Basic Energy Sciences of U.S. DOE.
文摘The recently discovered metal-intercalated iron selenide superconductors A2Fe4Se5 （A=K, Cs, T1- K, Rb, T1-Rb） （245） compounds, with Tc ～30K, have attracted much interest A high transition- temperature （TN ≈ 470-560K） and large magnetic moment （3.3μB/Fe） block antiferromagnetic （AFM） order exists in the superconducting samples. Mag- netic order-parameter experiences an anomaly when Tc is approached. The superconductors crystal- lize with a highly ordered √5 × √5 superstructure, in which the Fel site of the I4/m structure is only a few percents occupied and the Fe2 site is fully occupied. The non-superconducting samples at low-T also crystallize in the I4/m structure, while both Fe sites are fractionally occupied, since the numbers of the Fe vacancies in the samples and the vacant sites in the √5 × √5 pattern are mismatched. The partially ordered √5× √5 vacancy order becomes one of three competing phases for temperature below room temperature up to ～ 500K, namely, these sam- ples are phase-separated and in the miscibility gap 1lacier the n,mhi^nt condition.
基金Supported by the Innovation Program of Shanghai Municipal Education Commission(Grant No.2017-01-07-00-07-E00018)the Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)+1 种基金the National Natural Science Foundation of China(Grant No.11874119)the support of U.S.DOE BES Early Career Award No.KC0402020 under Contract No.DE-AC05-00OR22725。
文摘Van der Waals magnet VI_(3) demonstrates intriguing magnetic properties that render it great for use in various applications.However,its microscopic magnetic structure has not been determined yet.Here,we report neutron diffraction and susceptibility measurements in VI_(3) that revealed a ferromagnetic order with the moment direction tilted from the c-axis by ~36° at 4 K.A spin reorientation accompanied by a structure distortion within the honeycomb plane is observed,before the magnetic order completely disappears at TC=50 K.The refined magnetic moment of ~1.3μB at 4 K is much lower than the fully ordered spin moment of 2μB/V^(3+),suggesting the presence of a considerable orbital moment antiparallel to the spin moment and strong spin-orbit coupling in VI_(3).This results in strong magnetoelastic interactions that make the magnetic properties of VI_(3) easily tunable via strain and pressure.
