Magnetic order and crystal structure in the superconducting RNi{sub 2}B{sub 2}C materials

Journal Article · Sat Mar 01 00:00:00 EST 1997 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.55.6584· OSTI ID:505613

Lynn, J W; Skanthakumar, S ^[1]; Huang, Q ^[1]; Sinha, S K ^[2]; Hossain, Z; Gupta, L C; Nagarajan, R ^[3]; Godart, C ^[4]

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1. Reactor Radiation Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)
2. Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
3. Tata Institute of Fundamental Research, Bombay 400 005 (India)
4. CNRS, UPR-209, 92195 Meudon (France)

Neutron-diffraction measurements have been carried out to investigate the crystal structure, magnetic structures, and magnetic phase transitions in RNi{sub 2}B{sub 2}C(R= Y, Ce, Pr, Nd, Tb, Dy, Ho, Er, Tm, and Yb). The materials that order magnetically exhibit a wide variety of both commensurate and incommensurate magnetic structures, which argues strongly that the dominant exchange interactions are of the indirect Ruderman-Kittel-Kasuya-Yosida type. The Nd system exhibits a commensurate antiferromagnetic ordering at 4.8 K, with wave vector {delta}=(1/2,0,1/2) and moment direction along a (or equivalently with {delta}=(0,1/2,1/2) and moment direction along b in this tetragonal system). For Dy (T{sub N}=10.6K), Pr (T{sub N}=4.0K), and the low-temperature phase of Ho, the magnetic structure is also a commensurate antiferromagnet that consists of ferromagnetic sheets of rare-earth moments in the a-b plane, with the sheets coupled antiferromagnetically along the c axis [{delta}=(0,0,1)]. Pr is not superconducting, while for Dy (T{sub c}=6K) and Ho (T{sub c}=8K) this magnetic order coexists with superconductivity. For Ho, though, the magnetic state that initially forms at T{sub N}{approx}8.5K is an incommensurate spiral antiferromagnetic state along the c axis in which the direction of these ferromagnetic sheets are rotated in the a-b plane by {approximately}17{degree} from their low-temperature antiparallel configuration [{delta}=(0,0,0.91)]. The intensity for this spiral state reaches a maximum near the reentrant superconducting transition ({approximately}5K); the spiral state then collapses at lower temperature in favor of the commensurate antiferromagnetic state. An incommensurate a-axis modulation, with {delta}=(0.55,0,0), is also observed above the spiral-antiferromagnetic transition, but it exists over a narrower temperature range than the spiral state, and also collapses near the reentrant superconducting transition. (Abstract Truncated)

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• DOE Contract Number: AC05-96OR22464
• OSTI ID: 505613
• Journal Information: Physical Review, B: Condensed Matter, Vol. 55, Issue 10; Other Information: PBD: Mar 1997
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
SUPERCONDUCTORS
MAGNETIC PROPERTIES
RARE EARTH COMPOUNDS
CRYSTAL STRUCTURE
YTTRIUM COMPOUNDS
NICKEL COMPOUNDS
BORIDES
CARBIDES
MAGNETISM
NEUTRON DIFFRACTION
PHASE TRANSFORMATIONS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0000-0013 K
TEMPERATURE RANGE 0013-0065 K
spin density waves