Neutron Scattering Studies On Stoner Gap In The Superconducting Ferromagnet UGe2 By Using A Small Piston-Cylinder-Type Clamp Cell

Aso, Naofumi; Uwatoko, Y.; Fujiwara, T.; Motoyama, Gaku; S, Ban; Homma, Yoshiya; Shiokawa, Yoshinobu; Hirota, K.; Sato, Nobuya

doi:10.1063/1.2354902

Cited by 8 publications

(7 citation statements)

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“…1). In such a case, the experimetal results could be obscured by even a small pressure distribution within the sample [10,18].) Since it is unclear which is dominant, we tentatively tried to apply the Stoner model to the FM2 region.…”

Section: Resultsmentioning

confidence: 99%

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Stoner gap in the superconducting ferromagnetUGe2

et al. 2006

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We report the temperature (T ) dependence of ferromagnetic Bragg peak intensities and dc magnetization of the superconducting ferromagnet UGe2 under pressure (P ). We have found that the low-T behavior of the uniform magnetization can be explained by a conventional Stoner model. A functional analysis of the data produces the following results: The ferromagnetic state below a critical pressure can be understood as the perfectly polarized state, in which heavy quasiparticles occupy only majority spin bands. A Stoner gap ∆(P ) decreases monotonically with increasing pressure and increases linearly with magnetic field. We show that the present analysis based on the Stoner model is justified by a consistency check, i.e., comparison of density of states at the Fermi energy deduced from the analysis with observed electronic specific heat coeffieients. We also argue the influence of the ferromagnetism on the superconductivity.

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Section: Resultsmentioning

confidence: 99%

“…The pressure was generated using a copperberyllium (CuBe) based piston-cylinder clamp device [10] with Fluorinert FC-75 (3M Co. Ltd., Tokyo) as a pressure transmitting medium. The low temperature pressure was determined by measurements of the change in a lattice parameter of NaCl put together with the sample.…”

Section: Methodsmentioning

confidence: 99%

Stoner gap in the superconducting ferromagnetUGe2

et al. 2006

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“…For measurements with p < 2 GPa (experiment N1), a pistoncylinder cell was used, which is similar in design to the one in Ref. [44]. For measurements with p > 2 GPa (experiment N2), a clamp-type palm cubic anvil cell (PCAC) was used with ZrO 2 anvils and a gasket made out of an Al-based alloy [45].…”

Section: Experimental Methodsmentioning

confidence: 99%

“…For measurements with p < 2 GPa, a piston-cylinder cell was used, which is similar in design to the one in Ref. [44]. We refer to these experiments throughout the text as N1.…”

Section: F Neutron-diffraction Measurements At Hb1 On Single Crystalmentioning

confidence: 99%

Formation of short-range magnetic order and avoided ferromagnetic quantum criticality in pressurized LaCrGe3

et al. 2021

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LaCrGe3 has attracted attention as a paradigm example of the avoidance of ferromagnetic (FM) quantum criticality in an itinerant magnet. Here, we combined thermodynamic (specific heat and thermal expansion), transport, x-ray, and neutron scattering as well as μSR measurements to obtain insights on the temperature-pressure phase diagram of LaCrGe3. Consistent with previous studies of the phase diagram by transport measurements, our thermodynamic data shows clearly that the FM transition at TFM changes its character from second order to first order when it is suppressed to low temperatures by pressure. In addition, previous studies demonstrated that for high pressures a new phase occurs below T2, which was proposed to be a long-wavelength antiferromagnetic state (AFMq). In this paper, we provide evidence from our thermodynamic data that this phase transition is preceded by yet another phase transition at T1>T2. Our μSR data indicate that full magnetic volume fraction is only established below T2, but that this magnetism is characterized by a short correlation length. Within the experimental resolution, our neutron-scattering data is not able to identify any magnetic Bragg peaks. Overall, the microscopic magnetic data is therefore consistent with the formation of FM clusters in the proximity of the avoided FM quantum critical point in LaCrGe3. This conclusion is at odds with the previous proposal of AFMq order and raises questions on the role of disorder in this stochiometric compound.

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“…Thus, there exists a strong need to develop a smaller and more convenient pressure cell for LT ND measurements. Recently, we reported the design and basic properties of a small CuBe-based clamp cell for LT ND measurements, 4) and it was successfully used for studies of a pressure-induced superconducting ferromagnet UGe 2 , 5) a valence transition compound YbMn 2 Ge 2…”

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confidence: 99%