Low temperature phase transitions and magnetic structure of PrB6

McCarthy, C.M.; Tompson, C. W.; Graves, Rebecca; White, H. W.; Fisk, Z.; Ott, H. R.

doi:10.1016/0038-1098(80)90129-5

Cited by 56 publications

(22 citation statements)

References 6 publications

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“…We note that the magnitude q * of the incommensurate order should be influenced by the presence of other interactions neglected in this paper. Thus experimental and theoretical investigations to derive actual intersite interactions are desired in the near future.At zero temperature the saturated moment becomes |M | = 4/7 · A + ∼ 0.78µ B in the present theory, which is much larger than the observed value, 0.28µ B .2, 3) Thus, 23,31,32) in which there is no octupole moments within the Γ 5 CEF ground state. The comparative study between both compounds will be rewarding in future investigation.…”

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confidence: 57%

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Non-Collinear Magnetism due to Orbital Degeneracy and Multipolar Interactions

Kusunose

Kuramoto

2001

J. Phys. Soc. Jpn.

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The origin of non-collinear magnetism under quadrupolar ordering is investigated with CeB6 taken as a target system. The mode-mixing effect among 15 multipoles is analyzed based on the Ginzburg-Landau free energy. Then the lower magnetic transition temperature and the order parameters are derived within the mean-field approximation. In the presence of pseudodipole-type interactions for the next-nearest neighbors, the observed pattern of non-collinear ordering is indeed stabilized for certain set of interaction parameters. The stability of the phase III ′ in the magnetic field is also explained, which points to the importance of the next-nearestneighbor octupole-octupole interaction. Concerning the phase IV in CexLa1−xB6 with x ∼ 0.75, a possibility of pure octupole ordering is discussed based on slight modifications of the strength of interactions.KEYWORDS: orbital degeneracy, multipole moment, non-collinear magnetism, CeB 6 , CexLa 1−x B 6 , GinzburgLandau free energy, mode mixing §1. IntroductionFor the last decade, CeB 6 and Ce x La 1−x B 6 have attracted great interest because of their exotic properties originating from orbital degeneracy. Due to strong spin-orbit interaction of f electrons, the entangled spin and orbital degrees of freedom show unusual responses against various external perturbations.One of the mysteries was concerned with so-called phase II: (i) the inconsistency between NMR 1) and neutron scattering 2, 3) measurements on the pattern of the magnetic field induced antiferro (AF) magnetic moment and (ii) the increase of the transition temperature with increase of the magnetic field.1, 2, 4) The latter has been interpreted theoretically in terms of the intersite interaction between the field-induced Γ 2 -type octupole, i.e., T xyz , 5) and the quadrupolar fluctuations suppressed by the magnetic field.6, 7) The former mystery has been resolved by reconsidering the NMR analysis, where the coupling to the induced octupole in the hyperfine interaction is taken into account.8) Through these studies, the AF-quadrupolar ordering has been identified as of Γ 5 type (O yz , O zx , O xy ).In spite of these successful studies, understanding of phase III is still obscure. A complicated magnetic structure with double k, i.e., k 1 = (1/4, 1/4, 1/2) and k 2 = (1/4, −1/4, 1/2) in units of 2π/a with a being the lattice constant, has been established by neutron scattering.2, 3) The non-collinear spin orientation has no gain of energy from the nearest neighbor exchange interactions. Besides, the next-nearest neighbors give the same number of parallel and anti-parallel spins. Thus, the double k structure is hardly stabilized by simple exchange interactions. * E-mail: kusu@cmpt.phys.tohoku.ac.jp Furthermore, a new phase called IV was discovered recently in Ce x La 1−x B 6 with x ∼ 0.75, whose order parameter has not been identified yet. The phase IV has prominent features: (i) a drastic softening of the transverse elastic constant C 44 (∼ 30%), 9) (ii) almost no magneto resistance in contrast with other phases, 10...

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confidence: 57%

“…2, 3) Thus, 23,31,32) in which there is no octupole moments within the Γ 5 CEF ground state. The comparative study between both compounds will be rewarding in future investigation.…”

Section: ) §4 Summarymentioning

confidence: 99%

Non-Collinear Magnetism due to Orbital Degeneracy and Multipolar Interactions

Kusunose

Kuramoto

2001

J. Phys. Soc. Jpn.

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“…PrB 6 is a metal, which orders antiferromagnetically at low temperatures. The temperature dependence of heat capacity of PrB 6 in zero magnetic field [3,4] shows an extremely large peak at 6.9 K and a smaller peak at 4.2 K, which reveals two phase transitions in this compound. Neutron scattering data [3,5] indicate a spontaneous incommensurate magnetic ordering below 6.9 K and below 4.2 K a coexistence of commensurate and incommensurate phases.…”

Section: Introductionmentioning

confidence: 90%

“…At 1.74 K, only the commensurate phase is observed. Electrical resistivity and thermal conductivity (383) measurements [3,4,6] in zero magnetic field point to interesting transport properties at low temperatures in this compound. This was our motivation for the investigation of thermal conductivity and electrical resistivity of PrB 6 in various magnetic fields.…”

Section: Introductionmentioning

confidence: 98%

Magnetic Field Influence on the Thermal Conductivity of PrB₆

et al. 2008

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Results of thermal conductivity measurements on single crystalline PrB6 sample in the temperature range of 2-30 K and in magnetic field up to 14 T are presented. The obtained results are discussed in order to estimate the electron, phonon, and magnetic contributions to thermal conductivity. Taking into account the results of electrical resistivity of this compound the temperature dependence of the reduced Lorentz function is determined.

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“…Specific heat, thermal expansion, electrical resistivity [2] and magnetization [3] measurements show that second phase transition takes place at lower temperature T Q ∼ 4 K. The origin of latter one is a subject of intensive study and discussions. One of explanation relates this transition with the coexistence and competition between dipolar exchange and quadropolar interactions in presence of crystalline electric field (CEF) [3].…”

Section: Introductionmentioning

confidence: 98%