Volume-wise destruction of the antiferromagnetic Mott insulating state through quantum tuning

Frandsen, Benjamin A.; Liu, Lian; Cheung, Sky C.; Guguchia, Zurab; Khasanov, R.; Morenzoni, E.; Munsie, Timothy; Hallas, Alannah; Wilson, M. N.; Cai, Yipeng; Luke, G. M.; Chen, Bijuan; Li, Wenmin; Jin, Changqing; Ding, Cui; Guo, Shengli; Ning, Fanlong; Ito, Takashi U.; Higemoto, Wataru; Billinge, Simon J. L.; Sakamoto, Shoya; Fujimori, A.; Murakami, Taito; Kageyama, Hiroshi; Alonso, José Antonio; Kotliar, Gabriel; Imada, Masatoshi; Uemura, Y. J.

doi:10.1038/ncomms12519

Cited by 45 publications

(27 citation statements)

References 50 publications

(78 reference statements)

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“…This finding is consistent with the recent observation of first-order quantum evolution in the canonical bandwidth-controlled Mott insulators RENiO 3 and V 2 O 3 , despite the fact that no structural transition accompanies the MIT in BaCoS 2 . The similarity among disparate Mott systems suggests that first-order quantum phase transitions are ubiquitous in strongly correlated Mott systems, in agreement with previous theoretical predictions [15,[32][33][34][35][36].…”

Section: Discussionsupporting

confidence: 89%

Probing the quantum phase transition in Mott insulator BaCoS2 tuned by pressure and Ni substitution

Guguchia

Frandsen

Santos-Cottin

et al. 2019

Phys. Rev. Materials

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We present a muon spin relaxation study of the Mott transition in BaCoS2 using two independent control parameters: (i) pressure p to tune the electronic bandwidth and (ii) Ni-substitution x on the Co site to tune the band filling. For both tuning parameters, the antiferromagnetic insulating state first transitions to an antiferromagnetic metal and finally to a paramagnetic metal without undergoing any structural phase transition. BaCoS2 under pressure displays minimal change in the ordered magnetic moment S ord until it collapses abruptly upon entering the antiferromagnetic metallic state at pcr ∼1.3 GPa. In contrast, S ord in the Ni-doped system Ba(Co1−xNix)S2 steadily decreases with increasing x until the antiferromagnetic metallic region is reached at xcr ∼ 0.22. In both cases, significant phase separation between magnetic and nonmagnetic regions develops when approaching pcr or xcr, and the antiferromagnetic metallic state is characterized by weak, random, static magnetism in a small volume fraction. No dynamical critical behavior is observed near the transition for either tuning parameter. These results demonstrate that the quantum evolution of both the bandwidth-and filling-controlled metal-insulator transition at zero temperature proceeds as a first-order transition. This behavior is common to magnetic Mott transitions in RENiO3 and V2O3, which are accompanied by structural transitions without the formation of an antiferromagnetic metal phase.PACS numbers:

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Section: Discussionsupporting

confidence: 89%

Probing the quantum phase transition in Mott insulator BaCoS2 tuned by pressure and Ni substitution

Guguchia

Frandsen

Santos-Cottin

et al. 2019

Phys. Rev. Materials

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“…We note that phase separation of paramagnetic and magnetically ordered volumes is observed in many systems, including substitution-tuned (Sr,Ca)RuO 3 13 and RENiO 3 (RE = rare earth), pressure-tuned V 2 O 3 , 40 and high-T c cuprates with substitution and pressure tuning. 41,42 It may seem counter-intuitive to imagine that greater disorder could help restore sharp features and second-order criticality near a QCP, since disorder often "smears out" sharp features.…”

Section: Discussionmentioning

confidence: 83%

Restoration of quantum critical behavior by disorder in pressure-tuned (Mn,Fe)Si

et al. 2017

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In second-order quantum phase transitions from magnetically ordered to paramagnetic states at T = 0, tuned by pressure or chemical substitution, a quantum critical point is expected to appear with critical behavior manifesting in the slowing down of spin fluctuations in the paramagnetic state and a continuous development of the order parameter in the ordered state. Quantum criticality is discussed widely as a possible driving force for unconventional superconductivity and other exotic phenomena in correlated electron systems. In the real world, however, quantum critical points and quantum criticality are often masked by a preceding first-order transition and/or the development of competing states. Pressure tuning of the itinerant-electron helical magnet MnSi is a well-known example of the suppression of a quantum critical point due to a first-order phase transition and resulting destruction of the ordered state. Utilizing muon spin relaxation experiments, here we report that 15% Fe-substituted (Mn,Fe)Si exhibits completely different behavior with pressure tuning, including the restoration of second-order quantum critical behavior and a quantum critical point at p QPC~2 1-23 kbar, which coincides with the T = 0 crossing point of the extrapolated phase boundary line of pure MnSi. This result is quantitatively consistent with the recent theory of itinerant-electron ferromagnets by Sang, Belitz, and Kirkpatrick, who argued that disorder would restore a quantum critical point which is otherwise hidden by a firstorder transition.

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“…(2.6) now becomes 10) and the largest possible droplet size L c is the solution of the transcendental equation…”

Section: The Length Scale Lcmentioning

confidence: 99%

“…1 However, in many solid-state systems phase separation is observed by a variety of techniques -muon spin rotation (µSR), nuclear magnetic resonance (NMR), nuclear quadrupole resonance (NQR), neutron depolarization imaging, and neutron Larmor diffraction -even away from a coexistence curve. Examples include quantum ferromagnets and helimagnets such as MnSi, 2,3 9,10 In some of these systems the firstorder transition is from an ordered phase to a disordered phase (e.g., the ferromagnet-to-paramagnet transition in Sr 1−x Ca x RuO 3 , 4 or the transition from an antiferromagnetic insulator to a paramagnetic metal in the nickelates 9 ), in others, it is between two phases with the same order parameter (e.g., the FM1-FM2 transition between two ferromagnetic phases in UGe 2 .…”

Section: Introductionmentioning

confidence: 99%

Stable phase separation and heterogeneity away from the coexistence curve

Kirkpatrick

Belitz

2016

Phys. Rev. B

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Phase separation, i.e., the coexistence of two different phases, is observed in many systems away from the coexistence curve of a first-order transition, leading to a stable heterogeneous phase or region. Examples include various quantum ferromagnets, heavy-fermion systems, rare-earth nickelates, and others. These observations seem to violate basic notions of equilibrium thermodynamics, which state that phase separation can occur only on the coexistence curve. We show theoretically that quenched disorder allows for phase separation away from the coexistence curve even in equilibrium due to the existence of stable minority-phase droplets within the majority phase. Our scenario also answers a related question: How can a first-order transition remain sharp in the presence of quenched disorder without violating the rigorous lower bound ν ≥ 2/d for the correlation-length exponent? We discuss this scenario in the context of experimental results for a large variety of systems.

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Volume-wise destruction of the antiferromagnetic Mott insulating state through quantum tuning

Cited by 45 publications

References 50 publications

Probing the quantum phase transition in Mott insulator BaCoS2 tuned by pressure and Ni substitution

Probing the quantum phase transition in Mott insulator BaCoS2 tuned by pressure and Ni substitution

Restoration of quantum critical behavior by disorder in pressure-tuned (Mn,Fe)Si

Stable phase separation and heterogeneity away from the coexistence curve

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