Fermi surface reconstruction in FeSe under high pressure

Terashima, Taichi; Kikugawa, Naoki; Kiswandhi, Andhika; Graf, David; Choi, Eun Sang; Brooks, J. S.; Kasahara, S.; Watashige, Tatsuya; Matsuda, Yuji; Shibauchi, T.; Wolf, Thomas; Böhmer, Anna E.; Hardy, F.; Meingast, C.; Löhneysen, H. v.; Uji, Shinya

doi:10.1103/physrevb.93.094505

Cited by 55 publications

(85 citation statements)

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“…The current findings naturally match the observations of FeSe in neutron scattering 24,25 and high pressure experiments [31][32][33] , where the paramagnetic state of FeSe with substantial stripe spin fluctuations is identified to sit close to the stripe magnetic phase and may undergo a phase transition to the stripe magnetic ordered phase at high pressure. As FeSe is a bad metal that is in proximity of a Mott insulator, it would be interesting to consider the effects of itinerant electrons on the nematicity of the localized moments in further study.…”

Section: Discussion and Summarysupporting

confidence: 73%

“…Besides, FeSe possesses an electronic nematic order after a tetragonal-to-orthorhombic structural transition at T s 90K [19][20][21][22] . Although the primary origin of this nematic order is still unclear [23][24][25][26][27][28][29][30][31][32][33][34] , neutron scattering measurements indicate the important role of spin degree of freedom 24,25 . These novel properties have triggered wide interests in the magnetic ground state of FeSe [35][36][37][38][39][40][41][42][43][44][45] .…”

Section: Introductionmentioning

confidence: 99%

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Possible nematic spin liquid in spin-1 antiferromagnetic system on the square lattice: Implications for the nematic paramagnetic state of FeSe

et al. 2017

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The exotic normal state of iron chalcogenide superconductor FeSe, which exhibits vanishing magnetic order and possesses an electronic nematic order, triggered extensive explorations of its magnetic ground state. To understand its novel properties, we study the ground state of a highly frustrated spin-1 system with bilinearbiquadratic interactions using unbiased large-scale density matrix renormalization group. Remarkably, with increasing biquadratic interactions, we find a paramagnetic phase between Néel and stripe magnetic ordered phases. We identify this phase as a candidate of nematic quantum spin liquid by the compelling evidences, including vanished spin and quadrupolar orders, absence of lattice translational symmetry breaking, and a persistent non-zero lattice nematic order in the thermodynamic limit. The established quantum phase diagram natually explains the observations of enhanced spin fluctuations of FeSe in neutron scattering measurement and the phase transition with increasing pressure. This identified paramagnetic phase provides a new possibility to understand the novel properties of FeSe.

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Section: Discussion and Summarysupporting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Possible nematic spin liquid in spin-1 antiferromagnetic system on the square lattice: Implications for the nematic paramagnetic state of FeSe

et al. 2017

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“…The carrier density is one order-of-magnitude smaller than calculated. In the highpressure measurements up to 16.1 kbar [41], a drastic change in SdH oscillations has been found to occur at the onset of the AFM order at P ∼8 kbar: high SdH frequencies, corresponding to large FS cross sections, suddenly disappear, and only a low frequency remains. This suggests that parts of the FS is gapped by a reconstruction due to the AFM order.…”

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confidence: 99%

“…So far Shubnikovde Haas (SdH) measurements have been performed at ambient pressure [37][38][39][40] and under high pressure [41]. The Fermi surface (FS) at ambient pressure is anomalous, deviating significantly from that predicted by bandstructure calculations [37].…”

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confidence: 99%

Magnetotransport study of the pressure-induced antiferromagnetic phase in FeSe

Terashima¹,

Kikugawa²,

Kasahara³

et al. 2016

Phys. Rev. B

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The resistivity ρ and Hall resistivity ρH are measured on FeSe at pressures up to P = 28.3 kbar in magnetic fields up to B = 14.5 T. The ρ(B) and ρH (B) curves are analyzed with multicarrier models to estimate the carrier density and mobility as a function of P and temperature (T 110 K). It is shown that the pressure-induced antiferromagnetic transition is accompanied by an abrupt reduction of the carrier density and scattering. This indicates that the electronic structure is reconstructed significantly by the antiferromagnetic order.PACS numbers: 74.70. Xa, 72.15.Gd, 74.25.Dw, 74.25.Jb Since the discovery of superconductivity (SC) at T c = 26 K in LaFeAs(O 1−x F x ) by Kamihara et al.[1], the iron-based high-T c materials have intensively been studied. Yet, the paring mechanism is still highly controversial: some propose spin fluctuations as the glue [2, 3], while others orbital ones [4, 5]. Intimately related to this issue is the origin of the nematic transition [6]. Typical iron-pnictide parent compounds such as LaFeAsO or BaFe 2 As 2 [7,8] exhibit a tetragonal-toorthorhombic structural transition at T s , slightly above or at the same temperature as a stripe-type antiferromagnetic (AFM) order at T N . Electronic properties below T s exhibit in-plane anisotropy that is much stronger than expected from the slight orthorhombic distortion [9][10][11][12]. It is therefore believed that the structural transition is driven by electronic (i.e., spin or orbital) degrees of freedom and thus it is called a nematic transition. T s and T N are reduced simultaneously by pressure or chemical substitution, resulting in a phase diagram where the AFM phase is enclosed by the nematic one [9]. This is consistent with scenarios of spin-driven nematicity [6,13]. An SC dome appears around points where T s and T N reach zero.) initially attracted attention because of a remarkable enhancement of T c by pressure [15][16][17][18]. A report of T c > 50 K in single-layer films [19] has also aroused considerable interest. At the same time, FeSe may be crucial in determining the paring glue and the origin of the nematicity in the iron-based superconductors. It undergoes a structural transition at T s ∼ 90 K but does not order magnetically at ambient pressure [20]. A large splitting of the d xz and d yz bands below ∼ T s found by angle-resolved photoemission spectroscopy indicates that the transition at T s is a nematic one accompanied by orbital polarization [21][22][23]. An AFM transition can be induced by pressure [24][25][26]. However, the phase diagram (see Fig. 1 and [26][27][28]) is distinct from the typical one described above for the iron-pnictide compounds. This casts some doubts on the spin-nematic scenarios. It is however to be noted that low-energy AFM spin fluctuations have been observed below T s in NMR and inelastic neutron scattering measurements [29][30][31][32][33][34]. In addition, very recent reports suggest that at high pressures (P 18 kbar, Fig. 1) where no separate structural transition at T s is seen the AFM tr...

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“…Fig. 2 (c) shows K and the uniform magnetic susceptibility χ, measured in a vibrating sample magnetometer at 10 T. The relatively strong temperature dependence of K and χ is presumably due to the small Fermi-surface pockets found in FeSe [18,30,31] Fig. 2 (d) shows the spin-lattice relaxation rate divided by T , 1/T 1 T and Fig.…”

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confidence: 99%

Origin of the Tetragonal-to-Orthorhombic Phase Transition in FeSe: A Combined Thermodynamic and NMR Study of Nematicity

et al. 2015

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The nature of the tetragonal-to-orthorhombic structural transition at Ts ≈ 90 K in single crystalline FeSe is studied using shear-modulus, heat-capacity, magnetization and NMR measurements. The transition is shown to be accompanied by a large shear-modulus softening, which is practically identical to that of underdoped Ba(Fe,Co)2As2, suggesting very similar strength of the electronlattice coupling. On the other hand, a spin-fluctuation contribution to the spin-lattice relaxation rate is only observed below Ts. This indicates that the structural, or "nematic", phase transition in FeSe is not driven by magnetic fluctuations.PACS numbers: 74.70. Xa, 74.25.Bt, 74.25.Ld, 74.25.nj One of the most intriguing questions in the study of iron-based superconductors concerns the relation between structure, magnetism and superconductivity [1][2][3][4][5][6][7][8][9][10]. Stripe-type antiferromagnetic order often occurs at the same or at a slightly lower temperature than the tetragonal-to-orthorhombic structural distortion and the two types of order are closely related by symmetry. They break the four-fold rotational symmetry of the high-temperature phase, which can be associated with a nematic degree of freedom [4,6]. Superconductivity typically is strongest around the point where the structural transition (T s ) and the antiferromagnetic transition (T N ) are suppressed by pressure or chemical substitution. Whether the magnetic or the structural instability is the primary one, is still under intense debate [10], also because of its relevance to the pairing mechanism [5,6]. Recently, scaling relations between the shear modulus related to the structural distortion, C 66 , and the spinlattice relaxation time T 1 as a measure of the strength of spin fluctuations, have been proposed [7,8] in order to address the above question. They were found to be well satisfied in the Ba(Fe,Co) 2 As 2 system [7,8], where T s and T N are in close proximity to each other, suggesting a magnetically-driven structural transition [7]. Clearly, it is of great interest to see if a relation between shear modulus and spin fluctuations is universally observed in other iron-based materials.FeSe is structurally the simplest iron-based superconductor and has attracted a lot of attention because of a nearly four-fold increase of its T c ≈ 8 K under pressure [11]. Moreover, this system is particularly interesting with respect to the relation of structure and magnetism, since it undergoes a tetragonal-to-orthorhombic structural phase transition at T s ∼ 90 K, similar to that found in the 1111-and 122-type parent compounds [2], but does not order magnetically at ambient pressure [12,13]. Spin fluctuations at low temperatures were, however, observed in nuclear magnetic resonance (NMR) measurements [14]. Surprisingly, the orthorhombic distortion of FeSe is not reduced upon entering the superconducting state [9] in strong contrast to underdoped BaFe 2 As 2 [3,15], indicating different couplings between structure and superconductivity. This strongly motivates fu...

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Fermi surface reconstruction in FeSe under high pressure

Cited by 55 publications

References 70 publications

Possible nematic spin liquid in spin-1 antiferromagnetic system on the square lattice: Implications for the nematic paramagnetic state of FeSe

Possible nematic spin liquid in spin-1 antiferromagnetic system on the square lattice: Implications for the nematic paramagnetic state of FeSe

Magnetotransport study of the pressure-induced antiferromagnetic phase in FeSe

Origin of the Tetragonal-to-Orthorhombic Phase Transition in FeSe: A Combined Thermodynamic and NMR Study of Nematicity

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