Millikelvin-compatible apparatus for studies of quantum materials under uniaxial stress

Davino, D.; Franklin, Jacob; Sochnikov, Ilya

doi:10.1063/1.5130383

Cited by 3 publications

(2 citation statements)

References 19 publications

(26 reference statements)

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“…Building devices that will utilize the domains and domain walls to uncover useful electromagnetic behavior becomes a more realistic target with our findings: We show how magnetic domains form in CeAlSi, how they interact, and how they can be manipulated or stabilized with lattice strains estimated to be on picometer levels, which means it should be possible to induce such small strains externally using a strain cell and perhaps even enhance the ferromagnetic transition temperature. [ 49–52 ]…”

Section: Discussionmentioning

confidence: 99%

Picoscale Magnetoelasticity Governs Heterogeneous Magnetic Domains in a Noncentrosymmetric Ferromagnetic Weyl Semimetal

Franklin

Jayakody

et al. 2021

Adv Quantum Tech

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Magnetic Weyl semimetals are predicted to host emergent electromagnetic fields at heterogeneous strained phases or at the magnetic domain walls. Tunability and control of the topological and magnetic properties are crucial for revealing these phenomena, which are not well understood or fully realized yet. Here, a scanning superconducting quantum interference device microscope is used to image spontaneous magnetization and magnetic susceptibility of CeAlSi, a noncentrosymmetric ferromagnetic Weyl semimetal candidate. Large metastable domains are observed alongside stable ferromagnetic domains. The metastable domains most likely embody a type of frustrated or glassy magnetic phase, with excitations that may be of an emergent and exotic nature. Evidence is found that the heterogeneity of the two types of domains arises from magnetoelastic or magnetostriction effects. It is shown how these domains form, how they interact, and how they can be manipulated or stabilized with lattice strains estimated to be on picometer levels. This knowledge can be used in designing and fabricating devices made from CeAlSi and related materials for magnetic field sensing and magnetic memory applications.

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Section: Discussionmentioning

confidence: 99%

Picoscale Magnetoelasticity Governs Heterogeneous Magnetic Domains in a Noncentrosymmetric Ferromagnetic Weyl Semimetal

Franklin

Jayakody

et al. 2021

Adv Quantum Tech

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“…The experiments were performed on single crystals of Nb-doped strontium titanate, SrTi0.996Nb0.004O3, in a dilution refrigerator setup with a custom-built strain-stress cell [63] and a polarizing optical microscope [26]. Details of the basic characteristics of the samples are provided elsewhere [26].…”

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confidence: 99%

Giant Grüneisen parameter in a superconducting quantum paraelectric

Franklin

Davino

et al. 2021

Phys. Rev. B

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Superconductivity and ferroelectricity are typically thought of as incompatible because the former needs free carriers, but the latter is usually suppressed by free carriers. This is unless the carrier concentration is sufficiently low to allow for polar distortions and mobile electrons to cooperate. In the case of strontium titanate with low carrier concentration, superconductivity and ferroelectricity have been shown to be correlated via various tuning methods, such as strain. Here, we report theoretically and experimentally evaluated Grüneisen parameters whose divergent giant values under tensile stress indicate that the dominant phonon mode which enhances the superconducting order is the ferroelectric transverse soft phonon mode. This finding puts strong constraints on other phonon modes as the main contributors to the enhanced superconductivity in strained strontium titanate. The methodology shown here can be applied to strain-tune and probe properties of other materials with polar distortions including topologically non-trivial ones.

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Strain-engineered interaction of quantum polar and superconducting phases

Herrera

Cerbin

Jayakody

et al. 2019

Phys. Rev. Materials

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Much of the focus of modern condensed matter physics concerns control of quantum phases with examples that include flat band superconductivity in graphene bilayers (1), the interplay of magnetism and ferroelectricity (2), and induction of topological transitions by strain (3). Here we report the first observation of a reproducible and strong enhancement of the superconducting critical temperature, Tc, in strontium titanate (SrTiO3) obtained through careful strain engineering of interacting superconducting phase and the polar quantum phase (quantum paraelectric). Our results show a nearly 50% increase in Tc with indications that the increase could become several hundred percent. We have thus discovered a means to control the interaction of two quantum phases through application of strain, which may be important for quantum information science. Further, our work elucidates the enigmatic pseudogap-like and preformed electron pairs phenomena in low dimensional strontium titanate (4, 5) as potentially resulting from the local strain of jammed tetragonal domains. Main text:Among the main goals of this work is to address the open question of the nature of the superconducting pairing mechanism in strontium titanate (STO) (6, 7) and to inspire searches for enhanced superconducting temperatures in materials not just with suppressed to zero Kelvin structural transitions, as in (CaxSr1−x)3Rh4Sn13 (8), MoTe2 (9) and Lu(Pt1−xPdx)2In ( 10), but with incipient quantum phase transitions, for example, ScF3 which has a structural quantum phase transition (11), and may become superconducting when doped (12). It has been predicted that superconducting doped strontium titanate with its peculiar phonon dynamics (13-17) is an example of a superconductivity arising near an incipient quantum polar (quantum ferroelectric) phase transition (4,7,(18)(19)(20)(21)(22)(23)(24)(25)(26)(27), but this has not been fully demonstrated experimentally, in part, due to the fact that existing results on isotope effect and Ca substitution (25, 28) may be explained by non-uniformity in the chemical composition, and the absolute enhancement of the critical temperature values have not been found.It is also unusual to find a pseudogap-like behavior in superconductors that cannot be explained by compositional inhomogeneities, as is the case in cuprates (29). A pseudogap-like behaviors, such as a tunneling gap and a 2e charge transport, occur in STO at temperatures up to about 0.9 K, almost twice the bulk superconducting transition temperature (4, 5).

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Millikelvin-compatible apparatus for studies of quantum materials under uniaxial stress

Cited by 3 publications

References 19 publications

Picoscale Magnetoelasticity Governs Heterogeneous Magnetic Domains in a Noncentrosymmetric Ferromagnetic Weyl Semimetal

Picoscale Magnetoelasticity Governs Heterogeneous Magnetic Domains in a Noncentrosymmetric Ferromagnetic Weyl Semimetal

Giant Grüneisen parameter in a superconducting quantum paraelectric

Strain-engineered interaction of quantum polar and superconducting phases

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