Pressure As A Probe Of The Physics Of Compositionally-Substituted Quantum Paraelectrics: SrTiO3

Venturini, E. L.; Samara, G. A.; Itoh, Mitsuru; Kleemann, W.

doi:10.1063/1.1609931

Cited by 7 publications

(10 citation statements)

References 10 publications

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“…At this quantum critical point, the frequency of the polar transverse optical phonon mode responsible for the ferroelectric ordering approaches zero at the Brillouin zone center (29). Recent work (33) has shown that the magnitude of the dielectric loss peak at approximately 10 K, associated with quantum critical effects (34), is linked to the quantum critical point in agreement with results from oxygen-18 substituted SrTiO3 (9). An open question in the field remains as to the quantum phase transition empirically not becoming first order as temperature is lowered and lifting the quantum criticality (35).…”

Section: Significancesupporting

confidence: 79%

“…Another example involves a transition from a displacive ferroelectric state to an unpolarized or quantum paraelectric state in polar materials such as the perovskite oxides (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21). In contrast to the case of the magnetic metals, the nature of the unpolarized state in incipient ferroelectrics remains in some respects an enigma, especially in the lowtemperature regime.…”

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confidence: 99%

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Quantum critical phenomena in a compressible displacive ferroelectric

Coak

Haines

Liu

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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The dielectric and magnetic polarizations of quantum paraelectrics and paramagnetic materials have in many cases been found to initially increase with increasing thermal disorder and hence, exhibit peaks as a function of temperature. A quantitative description of these examples of “order-by-disorder” phenomena has remained elusive in nearly ferromagnetic metals and in dielectrics on the border of displacive ferroelectric transitions. Here, we present an experimental study of the evolution of the dielectric susceptibility peak as a function of pressure in the nearly ferroelectric material, strontium titanate, which reveals that the peak position collapses toward absolute zero as the ferroelectric quantum critical point is approached. We show that this behavior can be described in detail without the use of adjustable parameters in terms of the Larkin–Khmelnitskii–Shneerson–Rechester (LKSR) theory, first introduced nearly 50 y ago, of the hybridization of polar and acoustic modes in quantum paraelectrics, in contrast to alternative models that have been proposed. Our study allows us to construct a detailed temperature–pressure phase diagram of a material on the border of a ferroelectric quantum critical point comprising ferroelectric, quantum critical paraelectric, and hybridized polar-acoustic regimes. Furthermore, at the lowest temperatures, below the susceptibility maximum, we observe a regime characterized by a linear temperature dependence of the inverse susceptibility that differs sharply from the quartic temperature dependence predicted by the LKSR theory. We find that this non-LKSR low-temperature regime cannot be accounted for in terms of any detailed model reported in the literature, and its interpretation poses an empirical and conceptual challenge.

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Section: Significancesupporting

confidence: 79%

mentioning

confidence: 99%

Quantum critical phenomena in a compressible displacive ferroelectric

Coak

Haines

Liu

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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“…trontium titanate is an incipient ferroelectric insulator, which can be tuned essentially continuously into the ferroelectric phase via a 'quantum' tuning parameter, such as chemical substitution, isotopic substitution or applied stress (see, e.g., refs. [1][2][3][4][5][6][7] ). The temperature-quantum tuning parameter phase diagram of SrTiO 3 and related materials has recently been discussed in terms of a phenomenological model involving the interaction of the local ferroelectric order-parameter field with itself, and with the strain field of the lattice 3,S1-S13 (see Fig.…”

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confidence: 99%

“…The normalized superconducting transition temperature, T c calculated via the model given by Eqs. (1)-(5) and the material parameters relevant to SrTiO 3 (see "Methods" section), is shown (i) vs. pressure, p, for values of n around the superconducting dome (…”

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confidence: 99%

Superconductivity mediated by polar modes in ferroelectric metals

et al. 2020

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The occurrence of superconductivity in doped SrTiO3 at low carrier densities points to the presence of an unusually strong pairing interaction that has eluded understanding for several decades. We report experimental results showing the pressure dependence of the superconducting transition temperature, Tc, near to optimal doping that sheds light on the nature of this interaction. We find that Tc increases dramatically when the energy gap of the ferroelectric critical modes is suppressed, i.e., as the ferroelectric quantum critical point is approached in a way reminiscent to behaviour observed in magnetic counterparts. However, in contrast to the latter, the coupling of the carriers to the critical modes in ferroelectrics is predicted to be small. We present a quantitative model involving the dynamical screening of the Coulomb interaction and show that an enhancement of Tc near to a ferroelectric quantum critical point can arise due to the virtual exchange of longitudinal hybrid-polar-modes, even in the absence of a strong coupling to the transverse critical modes.

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“…An archetypical case is SrTiO 3 , in which a huge dielectric constant (e410 4 ) is observed at low temperatures (T) without showing any long-range order due to quantum fluctuations in the vicinity of a FE QCP [9][10][11] . Substituting 16 O with 18 O as well as applying external pressure have also been shown to be effective ways to control the FE transition temperature 12,13 .…”

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confidence: 99%

Manifestation of magnetic quantum fluctuations in the dielectric properties of a multiferroic

et al. 2014

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Insulating magnets can display novel signatures of quantum fluctuations as similar to the case of metallic magnets. However, their weak spin-lattice coupling has made such observations challenging. Here we find that antiferromagnetic (AF) quantum fluctuations manifest in the dielectric properties of multiferroic Ba 2 CoGe 2 O 7 , where a ferroelectric polarization develops concomitant to an AF ordering. Upon application of a magnetic field (H), dielectric constant shows a characteristic power-law dependence near absolute zero temperature and close to the critical field H c ¼ 37.1 T due to enhanced AF quantum fluctuations. When H4H c , the dielectric constant shows the temperature-dependent anomalies that reflect a crossover from a field-tuned quantum critical to a gapped spin-polarized state. We uncover theoretically that a linear relation between AF susceptibility and dielectric constant stems from the generic magnetoelectric coupling and directly explains the experimental findings, opening a new pathway for studying quantum criticality in condensed matter.

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Pressure As A Probe Of The Physics Of Compositionally-Substituted Quantum Paraelectrics: SrTiO3

Cited by 7 publications

References 10 publications

Quantum critical phenomena in a compressible displacive ferroelectric

Quantum critical phenomena in a compressible displacive ferroelectric

Superconductivity mediated by polar modes in ferroelectric metals

Manifestation of magnetic quantum fluctuations in the dielectric properties of a multiferroic

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