Coexistence of superconductivity and antiferromagnetism in (Li0.8Fe0.2)OHFeSe

Lu, Xingye; Wang, N. Z.; Wu, Hui; Wu, Yanfu; Zhao, Dan; Zeng, Xiaomei; Luo, Xiaoguang; Wu, Tao; Bao, Wan-Su; Zhang, G. H.; Huang, Fuqiang; Huang, Q.; Chen, X. H.

doi:10.1038/nmat4155

Cited by 363 publications

(337 citation statements)

References 28 publications

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“…with the growth of the twodimensional character of the materials. Most recently the active studies has started of [Li 1−x Fe x OH]FeSe system with the value of T c ∼43K [38,39], where a good enough single -phase samples and single crystals were obtained.…”

Section: Introductionmentioning

confidence: 99%

Electronic structure of FeSe monolayer superconductors

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Sadovskiǐ

et al. 2016

Low Temperature Physics

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We review a variety of theoretical and experimental results concerning electronic band structure of superconducting materials based on FeSe monolayers. Three type of systems are analyzed:intercalated FeSe systems A x Fe 2 Se 2−x S x and [Li 1−x Fe x OH]FeSe as well as the single FeSe layer films on SrTiO 3 substrate. We present the results of detailed first principle electronic band structure calculations for these systems together with comparison with some experimental ARPES data. The electronic structure of these systems is rather different from that of typical FeAs superconductors, which is quite significant for possible microscopic mechanism of superconductivity. This is reflected in the absence of hole pockets of the Fermi surface at Γ-point in Brillouin zone, so that there are no "nesting" properties of different Fermi surface pockets. LDA+DMFT calculations show that correlation effects on Fe-3d states in the single FeSe layer are not that strong as in most of FeAs systems. As a result, at present there is no theoretical understanding of the formation of rather "shallow" electronic bands at M points. LDA calculations show that the main difference in electronic structure of FeSe monolayer on SrTiO 3 substrate from isolated FeSe layer is the presence of the band of O-2p surface states of TiO 2 layer on the Fermi level together with Fe-3d states, which may be important for understanding the enhanced T c values in this system. We briefly discuss the implications of our results for microscopic models of superconductivity.

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Section: Introductionmentioning

confidence: 99%

Electronic structure of FeSe monolayer superconductors

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Sadovskiǐ

et al. 2016

Low Temperature Physics

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“…AFMs have a very fast dynamics, which allows for switching on ps timescale [14][15][16]. Furthermore, there exists a wide range of AFM materials, including many insulators and semiconductors, multiferroics [17] and superconductors [18]. Utilizing (and also studying) AFMs is difficult, largely because the magnetic order in AFMs is hard to detect and to manipulate.…”

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Spin-Polarized Current in Noncollinear Antiferromagnets

et al. 2017

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Noncollinear antiferromagnets, such as Mn3Sn and Mn3Ir, were recently shown to be analogous to ferromagnets in that they have a large anomalous Hall effect. Here we show that these materials are similar to ferromagnets in another aspect: the charge current in these materials is spin-polarized. In addition, we show that the same mechanism that leads to the spin-polarized current also leads to a transversal spin current, which has a distinct symmetry and origin from the conventional spin Hall effect. We illustrate the existence of the spin-polarized current and the transversal spin current by performing ab initio microscopic calculations and by analyzing the symmetry. Based on the spinpolarized current we propose an antiferromagnetic tunneling junction, analogous in functionality to the magnetic tunneling junction.Introduction. Spintronics is a field that studies phenomena in which both spin and charge degree of electron play an important role. Many of the key spintronics effects are based upon the existence of spin currents. Two main types of spin currents are utilized: the spin-polarized currents in ferromagnets (FMs) and the spin currents due to the spin Hall effect (SHE) which are transveral to the charge current and appear even in non-magnetic materials. The most important effects that originate from the spin-polarized currents in FMs are the giant and the tunneling magnetoresistance effects (GMR and TMR) [1][2][3] and the spin-transfer torque (STT) [4,5]. These effects are utilized in magnetic tunneling junctions (MTJs), which form the basic building block of a new type of solid state memory, the magnetic random access memory (MRAM) [6]. This memory is non-volatite and has speed and density comparable to the widely used dynamic random access memory. The SHE on the other hand is responsible (though other effects can contribute) for the spin-orbit torque (SOT) [7,8] in multilayer heterostructures, which can be used for efficient and fast switching of FM layers. The SOT is now also being explored for use in MRAMs [9,10].While spintronics has traditionally focused on FM and non-magnetic materials, in the past few years also antiferromagnetic (AFM) materials have attracted a considerable interest. AFMs offer some unique advantages compared to FMs, but are much less explored (see reviews [11][12][13]). AFMs have a very fast dynamics, which allows for switching on ps timescale [14][15][16]. Furthermore, there exists a wide range of AFM materials, including many insulators and semiconductors, multiferroics [17] and superconductors [18]. Utilizing (and also studying) AFMs is difficult, largely because the magnetic order in AFMs is hard to detect and to manipulate. Recently, electrical detection [19][20][21][22][23] and manipulation of the AFM order has been demonstrated [23,24], however, both detection and manipulation still remain challenging from a practical point of view.

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“…Figure 1 shows the neutron diffraction pattern for the 7 Li x Fe (1-x) ODFeSe sample collected at 4 K, which is the expected crystal structure analogous to that prepared in H 2 O. [28,30,32,35] Profile refinement of the tetragonal superconducting phase gave lattice constants a = 3.7827(1) Å, c = 9.1277(3) Å, and with x = 0.183 (6). A table of the refined parameters are provided in the supplemental material, together with room temperature x-ray data [36].…”

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“…[38] For the present system no evidence for antiferromagnetic ordering was found. [35] For a ferromagnet the magnetic Bragg peaks always occur at the same Bragg positions as the structural peaks, and we were also unable to detect any ordered ferromagnetic moment (see the supplemental material [36]). This perhaps is not surprising given that the ferromagnetism is expected to arise in the Li-Fe layer; with an expected moment of less than 1 μ B /Fe and only 18% of the sites occupied, the site-averaged ferromagnetic moment will be difficult to observe in powder diffraction.…”

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Neutron investigation of the magnetic scattering in an iron-based ferromagnetic superconductor

et al. 2015

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Neutron diffraction and small angle scattering experiments have been carried out on the doubleisotopic polycrystalline sample ( 7 Li 0.82 Fe 0.18 OD)FeSe. Profile refinements of the diffraction data establish the composition and reveal an essentially single phase material with lattice parameters of a= 3.7827 Å and c= 9.1277 Å at 4 K, in the ferromagnetic-superconductor regime, with a bulk superconducting transition of T C = 18 K. Small angle neutron scattering (SANS) measurements in zero applied field reveal the onset of ferromagnetic order below T F ≈ 12.5 K, with a wave vector and temperature dependence consistent with an inhomogeneous ferromagnet of spontaneous vortices or domains in a mixed state. No oscillatory long range ordered magnetic state is observed. Field dependent measurements establish a separate component of magnetic scattering from the vortex lattice, which occurs at the expected wave vector. The temperature dependence of the vortex scattering does not indicate any contribution from the ferromagnetism, consistent with diffraction data that indicate that the ordered ferromagnetic moment is quite small. PACS: 74.70.Xa, 74.25.Ha, 75.25.Uv; 75.25.-j *corresponding author. Jeffrey.Lynn@nist.gov 2 The magnetic properties of superconductors have a rich and interesting history. Early work showed that even tiny concentrations of magnetic impurities destroyed the superconducting pairing through the exchange-driven spin depairing mechanism, prohibiting any possibility of cooperative magnetic behavior.[1] The first exception to this rule was provided by the cubic rare-earth substituted CeRu 2 alloys [2][3][4], while the ternary Chevrel-phase (and related) superconductors (e.g. RMo 6 S 8 , R=rare earth) provided the first demonstrations of long range magnetic order coexisting with superconductivity. [5,6] The magnetic ordering temperatures were all quite low (~1 K), where electromagnetic (dipolar + London penetration depth) interactions play a dominate role in the energetics of the magnetic system. The vast majority of these materials order antiferromagnetically where coexistence of long range order with superconductivity was common, but these materials also provided the first examples of the rare occurrence of ferromagnetism and consequent competition with superconductivity in ErRh 4 B 4 , [7][8][9][10] HoMo 6 S 8 , [11][12][13] and HoMo 6 Se 8 .[14] Antiferromagnetic order is found for all the rare earths in the cuprates, which exhibit similar low ordering temperatures. [15] In the borocarbide superconductors again of all the magnetic order is antiferromagnetic, [16] with the singular exception of ErNi 2 B 2 C at low temperature [17,18] where a net magnetization developed that resulted in the spontaneous formation of flux quanta (vortices). [19,20] For the high-T C superconductors of direct interest here, there have been no ferromagnets in either the cuprate or iron-based systems, [15,[21][22][23] [28] For this latter system T C can be as high as 43 K, together with the development of magnetic ord...

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Coexistence of superconductivity and antiferromagnetism in (Li0.8Fe0.2)OHFeSe

Cited by 363 publications

References 28 publications

Electronic structure of FeSe monolayer superconductors

Electronic structure of FeSe monolayer superconductors

Spin-Polarized Current in Noncollinear Antiferromagnets

Neutron investigation of the magnetic scattering in an iron-based ferromagnetic superconductor

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