Neutron Scattering Study on UTGa{sub 5} and NpTGa{sub 5}

Conference · Sun Jul 01 04:00:00 EDT 2007

OSTI ID:21083701

Metoki, Naoto ^[1]

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1. Advanced Science Research Center, Japan Atomic Energy Agency, Tokai (Japan)

The results of our recent neutron scattering studies on actinide 115 compounds are reviewed. The itinerant many body f electron system and cross over to the localized character are realized only in actinide system. Actinide 115 family is very interesting, because we can grow high quality single crystals of many iso-structural compounds with different number and character of f electrons and valence d electrons. Variety of the ground state have been reported, e.g. paramagnetic, itinerant magnetism, and heavy fermion superconductivity in PuCoGa{sub 5}. Very recently we have intensively studied the magnetic structure in UTGa{sub 5} and NpTGa{sub 5}, These compounds exhibit a variety of the magnetic structure with A-, C-, G-type antiferromagnetic and ferromagnetic ordering and canted structure. NpFeGa{sub 5} exhibits an unusual magnetic anisotropy with the direction of the magnetic moment inclined about 25 degrees from the tetragonal basal plane. On the other hand, the localized compounds RRhIn{sub 5} (R: Tb, Ho, Dy, Nd) shows the antiferromagnetic structure with q=(1/2 0 1/2). The magnetic moment is parallel to the c-axis. An identical magnetic structure in rare earth compounds is a consequence of the localized nature of 4f electrons. We found that NpFeGa{sub 5}, NpNiGa{sub 5}, and NpRhGa{sub 5} exhibit 5f electronic transition between the low- and high-moment states associated with a change in the direction of the magnetic moment. The diverse magnetic ordering and the 5f electronic transition suggest that the orbital degree-of-freedom of itinerant 5f electrons may play important role for the physical properties in many body f electron systems. Actually a localized model predicts the magnetic structure and the phase diagram with magnetic and quadrupolar order parameters. A resonant X-ray scattering study is in progress, if the predicted anti-ferro-quadrupole order coexists with the canting antiferromagnetic dipole order in NpNiGa{sub 5}.

• Research Organization: Materials Research Society, 506 Keystone Drive, Warrendale, PA, 15086-7573 (United States)
• OSTI ID: 21083701
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANISOTROPY
ANTIFERROMAGNETISM
GALLIUM COMPOUNDS
MAGNETIC MOMENTS
MAGNETIZATION
MONOCRYSTALS
NEPTUNIUM COMPOUNDS
NEUTRON DIFFRACTION
ORDER PARAMETERS
PARAMAGNETISM
PHASE DIAGRAMS
SUPERCONDUCTIVITY
TRANSITION ELEMENT COMPOUNDS
URANIUM COMPOUNDS
X-RAY DIFFRACTION