Antiferromagnetic order induced by an applied magnetic field in
a high-temperature superconductor Kitaoka lab Itohara Keita
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Contents Introduction Meissner effect Type and Type
superconductor La 2-x Sr x CuO 4 Experimental method Magnetic
neutron diffraction Experimental data and discussions Summary
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Meissner effect Magnetic field H B=M+H=0
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Type and type superconductor Magnetic field H Type Type Normal
state Perfect diamagnetism Perfect diamagnetism Vortex state
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La 2-x Sr x CuO 4 Use single crystals of underdoped La 2-x Sr x
CuO 4 00.10.20.3 0 50 100 150 200 250 300 350 Temperature[K] Sr
doping (x) superconductivity Antiferromagnetism Spin glass
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Neutron diffraction Braggs law 2dsin= n Neutron diffraction is
closely related to X-ray powder diffraction Merit Neutrons have
stronger penetration than X-ray and interact directly with the
nucleus of the atom Samples sizes are relatively large compared to
those used in X-ray diffraction
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Magnetic neutron diffraction Neutrons are uncharged, they carry
a spin interact with magnetic moments reveal the microscopic
magnetic structure of a material
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Experimental data (1) Superconductivity characterized by
zero-resistivity at the much lower temperature T(K) T c =29K
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Experimental data (2) superconductivity and antiferro coexist
throughout the bulk of the material antiferromagnetism The applied
field that imposes the vortex lattice also induces
antiferromagnetic order
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Experimental data (3) The order increases rapidly with small
fields, reflecting the linear dependence of vortex density on field
Vortex core
Summary In the high-temperature superconductivity, La 2-x Sr x
CuO 4 (x=0.10),there is the field-induced antiferromagnetism The
field-induced antiferromagnetism is intrinsic And superconductivity
and antiferromagnetism coexist throughout the bulk of the material
00.10.20.3 0 50 100 150 200 250 300 350 Temperature[K] Sr doping
(x) superconductivity Antiferromagnetism Spin glass
