Direct observation of long range ferromagnetic order in the reentrant superconductor HoMo6S8

Lynn, J. W.; Moncton, D. E.; Thomlinson, W.; Shirane, G.; Shelton, R.N.

doi:10.1016/0038-1098(78)91295-4

Cited by 104 publications

(37 citation statements)

References 8 publications

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“…To second order, 1/(K + |k|) ≈ λe −|k|λ and K ≈ (1/λ)(1 + (kλ) 2 /2). Thus, the approximations in table I are good to three and two orders beyond leading order in k for cases (1), (3) and (2), (4), respectively. In the following, I discuss the far fields obtained from these approximations.…”

Section: Examplesmentioning

confidence: 84%

“…To understand those, it is useful to recall that for magnetostatic problems in the absence of macroscopic or supercurrents, −∇ 2 Φ = −4π∇ · M. Thus, ∇ · M acts as a magnetic charge by analogy with electrostatics. The field of a discontinuity of the in-plane component of M [case (1)] is just twice that of a magnetically charged line with linear charge density 4π 2M λ situated λ below the surface. It can be understood as the charge density due to the discontinuity of 2M in the magnetization, which is screened by supercurrents over one penetration depth.…”

Section: Examplesmentioning

confidence: 99%

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Magnetic fields above the surface of a superconductor with internal magnetism

Bluhm

2007

Phys. Rev. B

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The author presents a method for calculating the magnetic fields near a planar surface of a superconductor with a given intrinsic magnetization in the London limit. He computes solutions for various magnetic domain boundary configurations and derives relations between the spectral densities of the magnetization and the resulting field in the vacuum half space, which are useful if the magnetization can be considered as a statistical quantity and its features are too small to be resolved individually. The results are useful for analyzing and designing magnetic scanning experiments. Application to existing data from such experiments on Sr2RuO4 show that a domain wall would have been detectable, but the magnetic field of randomly oriented small domains and small defects may have been smaller than the experimental noise level.

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Section: Examplesmentioning

confidence: 84%

Section: Examplesmentioning

confidence: 99%

Magnetic fields above the surface of a superconductor with internal magnetism

Bluhm

2007

Phys. Rev. B

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“…More than three decades ago, several ferromagnets, such as ErRh 4 B 4 , 1) Chevrel phase compound HoMo 6 S 8 , 2) were already reported to show superconductivity, however, the Curie temperature T Curie is lower than the superconducting transition temperature T sc . When the ferromagnetic state is well established, the superconducting state is expelled, meaning that both phenomena are competitive each other.…”

Section: Introductionmentioning

confidence: 99%

“…UGe 2 is the first material which shows coexistence of ferromagnetism and superconductivity. 3) T Curie is suppressed with pressure and changes into the first order at tricritical point, and finally becomes zero at P c .…”

Section: Introductionmentioning

confidence: 99%

Superconductivity Reinforced by Magnetic Field and the Magnetic Instability in Uranium Ferromagnets

et al. 2011

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We review our recent results on ferromagnetic superconductors, URhGe and UCoGe. High quality single crystals of both compounds were successfully grown. The specific heat shows a clear jump related to the superconducting transition in UCoGe. The finite values of C/T at 0 K are discussed in terms of the selfinduced vortex state and the value of the ordered moment. With increasing fields for H b-axis in URhGe, the jump of thermal expansion increases and shifts to lower temperature. The re-entrant and S-shaped superconducting phases for URhGe and UCoGe respectively are explained by the unusual field dependence of the effective mass, which is induced by the ferromagnetic instability when the field is applied along the hard magnetization b-axis. The magnetic fluctuations are very sensitive to the field orientation. This is reflected in the H c2 and the anisotropy of the effective mass.

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“…The compounds are of special interest because they are also superconductors, and the connection between their superconductive and magnetic properties is the object of much current experimental (3)(4)(5)(6) and theoretical (7)(8)(9)(10) effort.…”

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confidence: 99%

Magnetic order and energetics of dipolar coupling in magnetic superconductors

Redi¹,

Anderson²

1981

Proc. Natl. Acad. Sci. U.S.A.

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The exact (notjust nearest-neighbor) dipolar coupling energy densities for the observed structures ofthe rare earth Chevrel compounds are calculated by the method ofLuttinger and Tisza. The dipolar coupling energy density for the most probable spin configuration is comparable to the observed magnetic transition temperature, TM, but the most probable ground state is not found experimentally. The discrepancy between the observed magnetic ground state and that predicted from dipole coupling may arise from conduction electron effects or possibly from some strong crystal field effect and should be included in any electronic theory of the superconductive state below TM.The antiferromagnetic interaction energy of the rare earth Chevrel (1) compounds is calculated on the basis of simple dipolar coupling (2). The compounds are of special interest because they are also superconductors, and the connection between their superconductive and magnetic properties is the object of much current experimental (3-6) and theoretical (7-10) effort.If the antiferromagnetic transition temperature, TM, could be accounted for by dipole coupling ofthe rare earth moments, the connection between superconductive and antiferromagnetic ordering would be simplified. Essentially, different electrons would give rise to the two effects.In the rare earth Chevrels, the magnetic moments are very large and well-separated spatially, and there is a relatively low density of conduction electrons. Thus, it seemed possible that the molecular field model of the transition temperature due only to dipole coupling could make a significant contribution to the stability ofthe magnetic phases ofthe rare earth Chevrels.The Chevrel compounds are characterized by sulfur cubes filled in alternate layers by Mo6 octahedra or metal, M,, each M-or Mo6-filled cube being separated from the next by an empty sulfur cube; the sulfur cubes themselves form a bodycentered cubic lattice. This structure permits the inclusion of a great variety of M,. When M. is a superconductor (Sn, Pb), the Chevrel compound is found to be superconducting with a raised transition temperature. The superconducting transition temperature, T,, is increased more for those with lowest original transition temperature, T%. If M. is not superconducting (Ag, Cu), the Chevrel compound becomes superconducting. If M. is a rare earth having a large free-ion magnetic moment, the Chevrel compounds exhibit both magnetic and superconducting ordering. In particular, TbMo6S8, DyMo6S8, and HoMo6S8 are found to be superconducting and at lower temperatures to exhibit antiferromagnetic and ferromagnetic order. METHOD OF LUTTINGER AND TISZAThe rare earth atoms lie on a nearly cubic lattice (rhombohedral angle a 89.40). The exact mean-field dipole coupling interaction energy for an ordered array of moments can be calculated by the group theoretic method of Luttinger and Tisza (11). A simple cubic dipole array is denoted by placing a dipole of definite moment and direction at every lattice point. The lowest energy-o...

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Direct observation of long range ferromagnetic order in the reentrant superconductor HoMo6S8

Cited by 104 publications

References 8 publications

Magnetic fields above the surface of a superconductor with internal magnetism

Magnetic fields above the surface of a superconductor with internal magnetism

Superconductivity Reinforced by Magnetic Field and the Magnetic Instability in Uranium Ferromagnets

Magnetic order and energetics of dipolar coupling in magnetic superconductors

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