Magnetic properties and magnetic structure of the Ba_(2)Mn(PO_(4))_(2) antiferromagnet featuring frustrated zigzag chains of S?52 Mn^(2+)ions are reported based on neutron diffraction,density-functional bandstructure ...Magnetic properties and magnetic structure of the Ba_(2)Mn(PO_(4))_(2) antiferromagnet featuring frustrated zigzag chains of S?52 Mn^(2+)ions are reported based on neutron diffraction,density-functional bandstructure calculations,as well as temperature-and field-dependent measurements of magnetization and specific heat.A magnetic transition at TN■5 K marks the onset of the antiferromagnetic order with the propagation vector k=(1/2 0 1/2)and the ordered moment of 4.33±0.08μB/Mn^(2+)at 1.5 K,pointing along the c direction.The direction of the magnetic moment is chosen by single-ion anisotropy,which is relatively weak compared to the isostructural Ni^(2+)compound.Geometrical frustration has a strong impact on the thermodynamic properties of Ba_(2)Mn(PO_(4))_(2),but manifestations of the frustration are different from those in Ba_(2)Ni(PO_(4))_(2),where frustration by isotropic exchange couplings is minor,yet strong and competing single-ion anisotropies are present.A spin-flop transition is observed around 2.5 T.The evaluation of the magnetic structure from the ground state via the spin-flop state to the field-polarized ferromagnetic state has been revealed by a comprehensive neutron diffraction study as a function of magnetic field below TN.Finally,a magnetic phase diagram in the H-T plane is obtained.展开更多
The topological insulators Bi_(2-x)Fe_(x)Se_(3-x)S_(x) have been investigated by the dc-magnetization,magnetotransport and angle resolved photoemission spectroscopy(ARPES)techniques.With doping of Fe and S,a negative ...The topological insulators Bi_(2-x)Fe_(x)Se_(3-x)S_(x) have been investigated by the dc-magnetization,magnetotransport and angle resolved photoemission spectroscopy(ARPES)techniques.With doping of Fe and S,a negative giant magneto-resistance(MR)is observed for parallel electric and magnetic fields(H||E).The MR behavior at lower magnetic field can be explained with the semi-classical theory whereas the MR behavior at higher field has been attributed to the axial anomaly.Interestingly,the system reached to the quantum limit at low magnetic field(~4.5T).The magnetic ordering can be explained with the presence of both the RKKY(surface)and van-Vleck(bulk)interaction.The ARPES study reveals that a surface gap is suppressed when the magnetic ordering changes from ferromagnetic to anti-ferromagnetic ordering.The ARPES study and the appearance of quantum oscillations(SdH)in the resistivity pattern reveal that the topological surface property is preserved with the co-doping of Fe and S.展开更多
文摘Magnetic properties and magnetic structure of the Ba_(2)Mn(PO_(4))_(2) antiferromagnet featuring frustrated zigzag chains of S?52 Mn^(2+)ions are reported based on neutron diffraction,density-functional bandstructure calculations,as well as temperature-and field-dependent measurements of magnetization and specific heat.A magnetic transition at TN■5 K marks the onset of the antiferromagnetic order with the propagation vector k=(1/2 0 1/2)and the ordered moment of 4.33±0.08μB/Mn^(2+)at 1.5 K,pointing along the c direction.The direction of the magnetic moment is chosen by single-ion anisotropy,which is relatively weak compared to the isostructural Ni^(2+)compound.Geometrical frustration has a strong impact on the thermodynamic properties of Ba_(2)Mn(PO_(4))_(2),but manifestations of the frustration are different from those in Ba_(2)Ni(PO_(4))_(2),where frustration by isotropic exchange couplings is minor,yet strong and competing single-ion anisotropies are present.A spin-flop transition is observed around 2.5 T.The evaluation of the magnetic structure from the ground state via the spin-flop state to the field-polarized ferromagnetic state has been revealed by a comprehensive neutron diffraction study as a function of magnetic field below TN.Finally,a magnetic phase diagram in the H-T plane is obtained.
基金Authors are grateful to CIF,IIT(BHU)for providing magnetic measurement facility.The ARPES measurements were performed with the approval of the Proposal Assessing Committee of the Hiroshima Synchrotron Radiation Center(Proposal Numbers:18AG029 and 18BG031).
文摘The topological insulators Bi_(2-x)Fe_(x)Se_(3-x)S_(x) have been investigated by the dc-magnetization,magnetotransport and angle resolved photoemission spectroscopy(ARPES)techniques.With doping of Fe and S,a negative giant magneto-resistance(MR)is observed for parallel electric and magnetic fields(H||E).The MR behavior at lower magnetic field can be explained with the semi-classical theory whereas the MR behavior at higher field has been attributed to the axial anomaly.Interestingly,the system reached to the quantum limit at low magnetic field(~4.5T).The magnetic ordering can be explained with the presence of both the RKKY(surface)and van-Vleck(bulk)interaction.The ARPES study reveals that a surface gap is suppressed when the magnetic ordering changes from ferromagnetic to anti-ferromagnetic ordering.The ARPES study and the appearance of quantum oscillations(SdH)in the resistivity pattern reveal that the topological surface property is preserved with the co-doping of Fe and S.
