Optimized unconventional superconductivity in a molecular Jahn-Teller metal

Zadik, R. H.; Takabayashi, Yasuhiro; Klupp, G.; Colman, R. H.; Ganin, Alexey Y.; Potočnik, Anton; Jeglič, P.; Arčon, Denis; Matus, Péter; Kamarás, Katalin; Kasahara, Yuichi; Iwasa, Yoshihiro; Fitch, Andrew N.; Ohishi, Yasuo; Garbarino, Gastón; Kato, Kenichi; Rosseinsky, Matthew J.; Prassides, Kosmas

doi:10.1126/sciadv.1500059

Cited by 113 publications

(183 citation statements)

References 32 publications

Supporting

Mentioning

167

Contrasting

Unclassified

Order By: Relevance

“…12 and 13 suggest that the alkali-doped fullerides are located near the transition between the metal and low-spin insulator (see box in Fig. 13), in agreement with experiments [49][50][51][52][53][54][55].…”

Section: A Two-orbital Model With Static Interactionssupporting

confidence: 82%

Double-expansion impurity solver for multiorbital models with dynamically screenedUandJ

Steiner¹,

Nomura²,

Werner³

2015

Phys. Rev. B

View full text Add to dashboard Cite

We present a continuous-time Monte Carlo impurity solver for multiorbital impurity models which combines a strong-coupling hybridization expansion and a weak-coupling expansion in the Hund's coupling parameter J . This double-expansion approach allows to treat the dominant density-density interactions U within the efficient segment representation. We test the approach for a two-orbital model with static interactions, and then explain how the double expansion allows to simulate models with frequency dependent U (ω) and J (ω). The method is used to investigate spin-state transitions in a toy model for fullerides, with repulsive bare J but attractive screened J .

show abstract

Section: A Two-orbital Model With Static Interactionssupporting

confidence: 82%

Double-expansion impurity solver for multiorbital models with dynamically screenedUandJ

Steiner¹,

Nomura²,

Werner³

2015

Phys. Rev. B

View full text Add to dashboard Cite

show abstract

“…We will argue that this unconventional SOSM state is realized in alkali-doped fullerides [5][6][7][8][9][10][11][12][13], which are promising candidates for diagonal odd-frequency orders. Several compounds in this class of materials can be regarded as strongly correlated systems since a Mott transition occurs as a function of pressure.…”

mentioning

confidence: 97%

“…As this state combines properties of the metal (connected to the weak-interaction limit) and Mott insulator (connected to the strong-interaction limit) it cannot be detected by perturbative methods from either limits, and its study requires the use of sophisticated techniques. The ordering phenomenon can be discussed in terms of a symmetry-breaking field or order parameter with odd time (frequency) dependence, and is hence related to the concept of odd-frequency superconductivity [1-4].We will argue that this unconventional SOSM state is realized in alkali-doped fullerides [5][6][7][8][9][10][11][12][13], which are promising candidates for diagonal odd-frequency orders. Several compounds in this class of materials can be regarded as strongly correlated systems since a Mott transition occurs as a function of pressure.…”

mentioning

confidence: 99%

“…Several compounds in this class of materials can be regarded as strongly correlated systems since a Mott transition occurs as a function of pressure. In the case of an fcc lattice [12], the Mott insulator stays paramagnetic in a wide range of temperature due to geometrical frustration, while it is antiferromagnetically ordered in the case of a bcc lattice, which is bipartite [11]. With increasing pressure, the system turns into a paramagnetic metal and is unstable to superconductivity below a maximum T c ≃ 38 K [11].…”

mentioning

confidence: 99%

See 1 more Smart Citation

Spontaneous Orbital-Selective Mott Transitions and the Jahn-Teller Metal of A3C60

Hoshino¹,

Werner²

2017

Phys. Rev. Lett.

View full text Add to dashboard Cite

The alkali-doped fullerides A3C60 are half-filled three-orbital Hubbard systems which exhibit an unconventional superconducting phase next to a Mott insulator. While the pairing is understood to arise from an effectively negative Hund coupling, the highly unusual Jahn-Teller metal near the Mott transition, featuring both localized and itinerant electrons, has not been understood. This property is consistently explained by a previously unrecognized phenomenon: the spontaneous transition of multiorbital systems with negative Hund coupling into an orbital-selective Mott state. This symmetry-broken state, which has no ordinary orbital moment, is characterized by an orbitaldependent two-body operator (the double occupancy) or an orbital-dependent kinetic energy, and may be regarded as a diagonal-order version of odd-frequency superconductivity. We propose that the recently discovered Jahn-Teller metal phase of RbxCs3−xC60 is an experimental realization of this novel state of matter.The appearance of long-range order by spontaneous symmetry breaking (SSB) is a fundamental and widely studied concept in physics. In condensed matter systems, the ordered state is typically characterized by an order parameter measuring the charge, magnetic moment, orbital angular momentum, or the pair amplitude in a superconductor. There may however exist more complex types of ordering phenomena. Here we demonstrate that in a certain class of multi-orbital systems one observes an orbital symmetry breaking into a state without conventional order parameter, but with an orbital-dependent double occupancy (a composite order parameter) and an orbital-dependent kinetic energy. The resulting ordered phase is a spontaneous orbital-selective Mott (SOSM) state, in which itinerant and localized electrons coexist. As this state combines properties of the metal (connected to the weak-interaction limit) and Mott insulator (connected to the strong-interaction limit) it cannot be detected by perturbative methods from either limits, and its study requires the use of sophisticated techniques. The ordering phenomenon can be discussed in terms of a symmetry-breaking field or order parameter with odd time (frequency) dependence, and is hence related to the concept of odd-frequency superconductivity [1-4].We will argue that this unconventional SOSM state is realized in alkali-doped fullerides [5][6][7][8][9][10][11][12][13], which are promising candidates for diagonal odd-frequency orders. Several compounds in this class of materials can be regarded as strongly correlated systems since a Mott transition occurs as a function of pressure. In the case of an fcc lattice [12], the Mott insulator stays paramagnetic in a wide range of temperature due to geometrical frustration, while it is antiferromagnetically ordered in the case of a bcc lattice, which is bipartite [11]. With increasing pressure, the system turns into a paramagnetic metal and is unstable to superconductivity below a maximum T c ≃ 38 K [11]. Recently, a so-called Jahn-Teller metal (JTM) state has bee...

show abstract

“…We note that such a large enhancement cannot be obtained by an overall increase of U/W for all of the orbitals, which would correspond to an isotropic volume control of the material [31]. Indeed, the chosen value U/W = 1 is already quite close to U/W ≃ 1.2 at which P sc is maximum, and only a very small enhancement of P sc can be obtained by increasing U/W (see also Fig.3).…”

Section: A Imbalanced Coulomb Interactionmentioning

confidence: 83%

Enhancing superconductivity inA3C60fullerides

et al. 2016

View full text Add to dashboard Cite

Motivated by the recent experimental report of a possible light-induced superconductivity in K3C60 at high temperature [Mitrano et al., Nature 530, 451 (2016)], we investigate theoretical mechanisms for enhanced superconductivity in A3C60 fullerenes. We find that an 'interaction imbalance' corresponding to a smaller value of the Coulomb matrix element for two of the molecular orbitals in comparison to the third one, efficiently enhances superconductivity. Furthermore, we perform firstprinciple calculations of the changes in the electronic structure and in the screened Coulomb matrix elements of K3C60 , brought in by the deformation associated with the pumped T1u intra-molecular mode. We find that an interaction imbalance is indeed induced, with a favorable sign and magnitude for superconductivity enhancement. The physical mechanism responsible for this enhancement consists in a stabilisation of the intra-molecular states containing a singlet pair, while preserving the orbital fluctuations allowing for a coherent inter-orbital delocalization of the pair. Other perturbations have also been considered and found to be detrimental to superconductivity. The light-induced deformation and ensuing interaction imbalance is shown to bring superconductivity further into the strong-coupling regime.

show abstract

Optimized unconventional superconductivity in a molecular Jahn-Teller metal

Abstract: A superconductivity dome is created by the electronic structure of the molecular building block of an unconventional superconductor.

Cited by 113 publications

References 32 publications

Double-expansion impurity solver for multiorbital models with dynamically screenedUandJ

Double-expansion impurity solver for multiorbital models with dynamically screenedUandJ

Spontaneous Orbital-Selective Mott Transitions and the Jahn-Teller Metal of A3C60

Enhancing superconductivity inA3C60fullerides

Contact Info

Product

Resources

About