Neutron diffraction studies of nuclear magnetic ordering in copper

Journal Article · Wed Mar 01 04:00:00 EST 1989 · J. Low Temp. Phys.; (United States)

OSTI ID:5892147

Jykkioe, T A; Huiku, M T; Siemensmeyer, K; Clausen, K N

The authors have constructed a two-stage nuclear demagnetization cryostat for neutron diffraction studies of nuclear magnetism in copper. The cryostat is combined with a two-axis neutron spectrometer which can cause both polarized and unpolarized neutrons. By demagnetizing highly polarized copper nuclear spins, the nuclei could be cooled below the ordering temperature T/sub N/ /approx equal/ 60 nK, while keeping the lattice at a considerably higher temperature between 50 and 100 /mu/K. The neutron beam increases the lattice temperature in the sample by a factor or two or more, thereby considerably shortening the time for measurements in the ordered state; both their calculations and the experiments yield 1 nW beam heating. Polarized neutron experiments show that the scattered intensities from the strong fcc reflections are severely reduced by extinction. This makes the sample not very suitable for further studies with polarized neutrons. By observing the (100) Bragg reflection, they have unambiguously proven antiferromagnetic ordering of the copper nuclear spins. Using a linear, position-sensitive detector, the time evolution of this peak was followed during the warm-up of the nuclear spin system. The peak intensity was found to depend strongly on the external magnetic field between zero and the critical field B/sub c/ = 0.25 mT, indicating the existence of at least two antiferromagnetic phases. The results are compared to previous measurements of the magnetic susceptibility. Theoretical calculations do not provide a full explanation for their experimental data.

• Research Organization: Helsinki Univ. of Technology, Espoo (Finland)
• OSTI ID: 5892147
• Journal Information: J. Low Temp. Phys.; (United States), Journal Name: J. Low Temp. Phys.; (United States) Vol. 74:5-6; ISSN JLTPA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
360104 -- Metals & Alloys-- Physical Properties
360106 -- Metals & Alloys-- Radiation Effects
420201 -- Engineering-- Cryogenic Equipment & Devices
651620 -- Nuclear Properties & Reactions
A=59-89
Experimental
654003 -- Radiation & Shielding Physics-- Neutron Interactions with Matter
656002 -- Condensed Matter Physics-- General Techniques in Condensed Matter-- (1987-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ADIABATIC DEMAGNETIZATION
AMPLITUDES
ANGULAR MOMENTUM
ANTIFERROMAGNETISM
BARYON REACTIONS
BEAMS
BRAGG REFLECTION
COHERENT SCATTERING
CONTROL EQUIPMENT
COPPER
COPPER 63 TARGET
COPPER 65
COPPER 65 TARGET
COPPER ISOTOPES
COUPLING
CRYOSTATS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CUBIC LATTICES
DECAY
DIFFRACTION
ELEMENTS
EQUIPMENT
FCC LATTICES
HADRON REACTIONS
INTERMEDIATE COUPLING
INTERMEDIATE MASS NUCLEI
ISOTOPES
J-J COUPLING
MAGNETIC FIELDS
MAGNETIC PROPERTIES
MAGNETIC SUSCEPTIBILITY
MAGNETISM
MEASURING INSTRUMENTS
METALS
NEUTRON DIFFRACTION
NEUTRON REACTIONS
NEUTRON SPECTROMETERS
NUCLEAR REACTIONS
NUCLEI
NUCLEON REACTIONS
ODD-EVEN NUCLEI
ORDER PARAMETERS
ORDER-DISORDER TRANSFORMATIONS
ORIENTATION
PARTICLE PROPERTIES
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
PHYSICAL RADIATION EFFECTS
POLARIZED BEAMS
RADIATION EFFECTS
REFLECTION
SCATTERING
SCATTERING AMPLITUDES
SPECTROMETERS
SPIN
SPIN ORIENTATION
STABLE ISOTOPES
TARGETS
TEMPERATURE EFFECTS
THERMOSTATS
TRANSITION ELEMENTS
ULTRALOW TEMPERATURE