Superconductivity in the non-magnetic state of iron under pressure

Shimizu, Katsuya; Kimura, Taishi; Furomoto, Shigeyuki; Takeda, Keiki; Kontani, Kazuyoshi; Ōnuki, Yoshichika; Amaya, Kiichi

doi:10.1038/35085536

Cited by 279 publications

(227 citation statements)

References 8 publications

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“…[3][4][5][6] Moreover, a considerable number of iron-based compounds have been reported as exhibiting superconductivity, including inter-metallic compounds (U 6 Fe, Th 7 Fe [7,8]), iron silicates (R 2 Fe 3 Si 5 , R = Sc, Y, Lu, and Tm [9,10]), and rare-earth-filled skutterudites (LnFe 4 P 12 , Ln = La, Y [11,12]) whose transition temperatures (T c ) range from 1.8 to 7 K. All of these compounds show Pauli paramagnetic behavior in the normal conducting states, indicating that the magnetic moments of the irons are quenched. The quench of the magnetic moment is also observed in a high-pressure phase of elementary iron ε-Fe, which shows a superconducting transition at ~2 K. [13] We have recently found that LaOFeP exhibits metallic conduction near room temperature and undergoes a superconducting transition at ~4 K, [14] providing a new compound system to the iron-based superconductors.…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic properties and electronic structure of the iron-based layered superconductor LaFePO

et al. 2008

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Section: Introductionmentioning

confidence: 99%

Electromagnetic properties and electronic structure of the iron-based layered superconductor LaFePO

et al. 2008

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“…The recent reports of the coexistence of ferromagnetism and superconductivity in UGe 2 [1], ZrZn 2 [2], URhGe [3] as well as the discovery of superconductivity in the non-magnetic hcp phase of Fe under pressure [4] have reopened the debate regarding the relationship of magnetism and superconductivity. Motivated by the case of liquid 3 He, the search for superconductivity mediated by spin fluctuations in nearly magnetic materials has a long history [5].…”

mentioning

confidence: 99%

Heavy Quasiparticles in the Ferromagnetic SuperconductorZrZn2

et al. 2003

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We report a study of the de Haas-van Alphen effect in the normal state of the ferromagnetic superconductor ZrZn2. Our results are generally consistent with an LMTO band structure calculation which predicts four exchange-split Fermi surface sheets. Quasiparticle effective masses are enhanced by a factor of about 4.9 implying a strong coupling to magnetic excitations or phonons. Our measurements provide insight in to the mechanism for superconductivity and unusual thermodynamic properties of ZrZn2.The recent reports of the coexistence of ferromagnetism and superconductivity in A detailed knowledge of the electronic structure of ZrZn 2 is crucial to the understanding of both its normal and superconducting properties. Thus we report here a detailed study of the Fermi surface (FS) made using angle-resolved measurements of the de Haas-van Alphen effect (dHvA). Our results are compared with an ab-initio electronic structure calculation. We observe much of calculated Fermi surface which consists of four exchangesplit sheets. Our study shows that ZrZn 2 is characterized by a large quasiparticle density-of-states (DOS) at the Fermi energy in the ferromagnetic state, which arises partly from the band structure and partly from a large mass enhancement.ZrZn 2 has many unusual properties. Below T FM = 28.5 K it becomes ferromagnetic with an ordered moment of 0.17µ B per formula unit at low temperatures (T = 2 K). The intrinsic moment is unsaturated, with an applied magnetic field of 6 Tesla causing a 50% increase. Compared with other d-band metals, it has an extremely large electronic heat capacity at low temperatures C/T = 47 mJK −2 mol −1 . ZrZn 2 crystallizes in the C15 cubic Laves structure, with lattice constant a = 7.393Å, the Zr atoms forming a tetrahedrally co-ordinated diamond structure. Its magnetic properties derive from the Zr 4d orbitals, which have a significant direct overlap.Interest in ZrZn 2 has been rekindled by the discovery that it is superconducting at ambient pressure and that both the superconductivity and ferromagnetism are simultaneously destroyed by the application of hydrostatic pressure. For the samples considered here, the onset temperature for the superconductivity is T SC ≈ 0.6 K with B c2 ≈ 0.9 T. The most striking feature of ZrZn 2 , UGe 2 and URhGe is perhaps that the same electrons are thought to participate both to superconductivity and ferromagnetism, in contrast with the situation in other "magnetic" superconductors e.g. borocarbides, RuSr 2 GdCu 2 O 8 [9], where the magnetism and superconductivity occur in different parts of the unit cell. Furthermore, ZrZn 2 is a three-dimensional intermetallic compound in which the itineracy of the d-electrons is almost unquestionable, whereas some doubts remain about that of the 5f electrons and roles of the strong magnetocrystalline anisotropy and quasi-two-dimensional electronic structure in UGe 2 and URhGe.The dHvA effect is due to the quantization of the cyclotron motion of charge carriers and results in a magnetization, M osc , which oscillates ...

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“…The sharpness of the transitions is taken as evidence that both transitions are first order. At pressures above that required to drive iron into the non-magnetic phase, superconductivity appears and passes through a broad maximum of ∼2 K near 20 GPa [221]. The fact that the superconductivity only appears in the non-magnetic phase (exactly the opposite of the situation for UGe 2 ) might lead one to conclude that iron is a conventional superconductor since the onset of ferromagnetism immediately destroys the superconductivity.…”

Section: Ferromagnetic Superconductorsmentioning

confidence: 97%

“…Upon further increase of pressure, the ordered moment drops abruptly in the Fig. 22 (a) Structural, magnetic, and superconducting phases of iron as a function of pressure [20,31,221]. The superconducting critical temperature has been multiplied by a factor of 100 to make it more visible.…”

Section: Ferromagnetic Superconductorsmentioning

confidence: 99%

Non-Fermi Liquid Regimes and Superconductivity in the Low Temperature Phase Diagrams of Strongly Correlated d- and f-Electron Materials

et al. 2010

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Standard models for simple metals and insulators often fail for systems based on elements with unstable d-or f -electron shells, where strong electronic correlations can generate new and unexpected states of matter. Such a scenario can often be induced when a magnetic phase transition is tuned to absolute zero temperature by an external control parameter such as chemical composition, pressure or magnetic field. At the resulting quantum critical point (QCP), emergent phenomena, such as unconventional superconductivity and novel magnetic phases are frequently observed. The temperature and energy dependences of the physical properties are also found to deviate from expectations for a simple Fermi liquid. This "non-Fermi-liquid" (NFL) behavior is commonly manifested as weak power laws and logarithmic divergences in the physical properties at low temperatures and is often found in a V-shaped region near a QCP, which has become the "classic" QCP phase diagram. However, there is also a growing number of materials where the NFL behavior either occurs far away from the QCP, within an ordered phase, or may not be associated with any putative QCP. Thus, after nearly 20 years of research, it remains unknown whether NFL physics is universal, or if a multitude of unique subclasses exist. In this article, we review research that has primarily been carried out in our laboratory on systems that exhibit NFL behavior that does not conform to the "classic" QCP scenario.

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Superconductivity in the non-magnetic state of iron under pressure

Cited by 279 publications

References 8 publications

Electromagnetic properties and electronic structure of the iron-based layered superconductor LaFePO

Electromagnetic properties and electronic structure of the iron-based layered superconductor LaFePO

Heavy Quasiparticles in the Ferromagnetic SuperconductorZrZn2

Non-Fermi Liquid Regimes and Superconductivity in the Low Temperature Phase Diagrams of Strongly Correlated d- and f-Electron Materials

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