Structural and magnetic aspects of the metal-insulator transition in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Ca</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn><mml:mi>−</mml:mi><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Sr</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant

Friedt, O.; Braden, M.; André, G.; Adelmann, P.; Nakatsuji, Satoru; Maeno, Y.

doi:10.1103/physrevb.63.174432

Cited by 267 publications

(319 citation statements)

References 27 publications

(48 reference statements)

Supporting

Mentioning

288

Contrasting

Unclassified

Order By: Relevance

“…Furthermore, we verified that the structure corresponds to the so-called D-Pbca phase and not to the L-Pbca phase, which is in close proximity in the phase diagram. 15 (These two structural phases correspond to the two possible senses of rotation of next-nearest layers with respect to each other; it is the same in L-Pbca and opposite in D-Pbca, which causes a doubling of the c lattice parameter. 15 )…”

Section: Samples and Experimental Aspectsmentioning

confidence: 99%

“…15 (These two structural phases correspond to the two possible senses of rotation of next-nearest layers with respect to each other; it is the same in L-Pbca and opposite in D-Pbca, which causes a doubling of the c lattice parameter. 15 )…”

Section: Samples and Experimental Aspectsmentioning

confidence: 99%

“…This notation neglects the structural distortions-a rotation of the RuO 6 octahedra around the vertical axis and an additional tilt in the case of x = 0.2 (Ref. 15)-that have to be described in a larger unit cell ( √ 2a √ 2a 2c). Samples were well characterized by neutron diffraction; in particular, by regarding characteristic superstructure reflections of the structural distortions, we can state that the Ca 1.8 Sr 0.2 RuO 4 sample was twinned with approximately equal amounts of both twins.…”

Section: Samples and Experimental Aspectsmentioning

confidence: 99%

See 2 more Smart Citations

Magnetic excitations in the metallic single-layer ruthenates Ca2−xSrxRuO
Steffens
¹
,
Friedt
²
,
Sidis
³

et al. 2011
Phys. Rev. B
Self Cite

View full text Add to dashboard Cite

By inelastic neutron scattering, we have analyzed the magnetic correlations in the paramagnetic metallic region of the series Ca 2−x Sr x RuO 4 , 0.2 x 0.62. We find different contributions that correspond to twodimensional ferromagnetic fluctuations and to fluctuations at incommensurate wave vectors Q IC 1 = (0.11,0,0), Q IC 2 = (0.26,0,0), and Q IC αβ = (0.3,0.3,0). These components constitute the measured response as a function of the Sr concentration x, of the magnetic field, and of the temperature. A generic model is applicable to metallic Ca 2−x Sr x RuO 4 close to the Mott transition, in spite of their strongly varying physical properties. The amplitude, characteristic energy, and width of the incommensurate components vary only slightly as functions of x, but the ferromagnetic component depends sensitively on concentration, temperature, and magnetic field. While ferromagnetic fluctuations are very strong in Ca 1.38 Sr 0.62 RuO 4 with a low characteristic energy of 0.2 meV at T = 1.5 K, they are strongly suppressed in Ca 1.8 Sr 0.2 RuO 4 , but reappear upon the application of a magnetic field, and form a magnon mode above the metamagnetic transition. The inelastic neutron scattering results document how the competition between ferromagnetic and incommensurate antiferromagnetic instabilities governs the physics of this system.

show abstract

Section: Samples and Experimental Aspectsmentioning

confidence: 99%

Section: Samples and Experimental Aspectsmentioning

confidence: 99%

Section: Samples and Experimental Aspectsmentioning

confidence: 99%

See 1 more Smart Citation

Magnetic excitations in the metallic single-layer ruthenates Ca2−xSrxRuO
Steffens
¹
,
Friedt
²
,
Sidis
³

et al. 2011
Phys. Rev. B
Self Cite

View full text Add to dashboard Cite

show abstract

“…1). Because the local symmetry around the Ru(IV) ion is very low 8,9 (having only inversion symmetry), it is widely believed that the orbital moment is completely quenched by the crystalline electric field [10][11][12][13] , which is dominated by the compressive distortion of the RuO 6 octahedra along the c-axis (Fig. 1).…”

mentioning

confidence: 99%

Higgs mode and its decay in a two-dimensional antiferromagnet

et al. 2017

View full text Add to dashboard Cite

Condensed-matter analogues of the Higgs boson in particle physics allow insights into its behaviour in di erent symmetries and dimensionalities 1 . Evidence for the Higgs mode has been reported in a number of di erent settings, including ultracold atomic gases 2 , disordered superconductors 3 , and dimerized quantum magnets 4 . However, decay processes of the Higgs mode (which are eminently important in particle physics)have not yet been studied in condensed matter due to the lack of a suitable material system coupled to a direct experimental probe. A quantitative understanding of these processes is particularly important for low-dimensional systems, where the Higgs mode decays rapidly and has remained elusive to most experimental probes. Here, we discover and study the Higgs mode in a two-dimensional antiferromagnet using spin-polarized inelastic neutron scattering. Our spin-wave spectra of Ca 2 RuO 4 directly reveal a well-defined, dispersive Higgs mode, which quickly decays into transverse Goldstone modes at the antiferromagnetic ordering wavevector. Through a complete mapping of the transverse modes in the reciprocal space, we uniquely specify the minimal model Hamiltonian and describe the decay process. We thus establish a novel condensed-matter platform for research on the dynamics of the Higgs mode.For a system of interacting spins, amplitude fluctuations of the local magnetization-the Higgs mode-can exist as well-defined collective excitations near a quantum critical point (QCP). We consider here a magnetic instability driven by the intra-ionic spinorbit coupling, which tends towards a non-magnetic state through complete cancellation of orbital (L) and spin (S) moments when they are antiparallel and of equal magnitude 5,6 . This mechanism should be broadly relevant for d 4 compounds of such ions as Ir(V), Ru(IV), Os(IV) and Re(III) with sizable spin-orbit coupling but remains little explored. We investigate the magnetic insulator Ca 2 RuO 4 , a quasi-two-dimensional antiferromagnet 7 with nominally L = 1 and S = 1 (Fig. 1). Because the local symmetry around the Ru(IV) ion is very low 8,9 (having only inversion symmetry), it is widely believed that the orbital moment is completely quenched by the crystalline electric field 10-13 , which is dominated by the compressive distortion of the RuO 6 octahedra along the c-axis (Fig. 1). In the absence of an orbital moment, the nearest-neighbour magnetic exchange interaction is necessarily isotropic. Deviations from this behaviour are a sensitive indicator of an unquenched orbital moment. If this moment is sufficiently strong, it can drive Ca 2 RuO 4 close to a QCP with novel Higgs physics.Our comprehensive set of time-of-flight (TOF) inelastic neutron scattering (INS) data over the full Brillouin zone (Fig. 2a) indeed reveal qualitative deviations of the transverse spin-wave dispersion from those of a Heisenberg antiferromagnet. In particular, the global maximum of the dispersion is found at q = (0,0), in sharp contrast to a Heisenberg antiferromagnet, which has a...

show abstract

“…It is not clear what causes this dramatic change in magnetic correlations, but it may be related to a loss in c-axis electronic coherence, which reveals itself as a steep rise in the c-axis resistivity in this temperature region [6]. It is of interest that in the compound Ca 2−x Sr x RuO 4 [21,22], doping with Sr drives the system from an insulating antiferromagnetic state, through a phase with a ferromagnetic instability to a metallic superconducting one. In contrast, in Sr 3 Ru 2 O 7 the competing interactions coexist in the same high-quality stoichiometric samples.…”

mentioning

confidence: 99%

Observation of two-dimensional spin fluctuations in the bilayer ruthenateSr3Ru2O

et al. 2003

Self Cite

View full text Add to dashboard Cite

We report the first observation of two-dimensional incommensurate magnetic fluctuations in the layered metallic perovskite Sr3Ru2O7. The wavevectors where the magnetic fluctuations are strongest are different from those observed in the superconducting single layer ruthenate Sr2RuO4 and appear to be determined by Fermi surface nesting. No antiferromagnetic ordering is observed for temperatures down to 1.5 K. For temperatures T > ∼ 20 K, the fluctuations become predominately ferromagnetic. Our inelastic neutron scattering measurements provide concrete evidence of the coexistence of competing interactions in Sr3Ru2O7 and of the low energy scale of the fluctuations.78.70. Nx, 75.40.Gb, 74.20.Mn, 75.30.Kz

show abstract

Structural and magnetic aspects of the metal-insulator transition inCa2−xSrx

Cited by 267 publications

References 27 publications

Magnetic excitations in the metallic single-layer ruthenates Ca2−xSrxRuO
Steffens
¹
,
Friedt
²
,
Sidis
³

et al. 2011
Phys. Rev. B
Self Cite

Magnetic excitations in the metallic single-layer ruthenates Ca2−xSrxRuO
Steffens
¹
,
Friedt
²
,
Sidis
³

et al. 2011
Phys. Rev. B
Self Cite

Higgs mode and its decay in a two-dimensional antiferromagnet

Observation of two-dimensional spin fluctuations in the bilayer ruthenateSr3Ru2O

Contact Info

Product

Resources

About

Structural and magnetic aspects of the metal-insulator transition inCa2−xSrx

Cited by 267 publications

References 27 publications

Magnetic excitations in the metallic single-layer ruthenates Ca2−xSrxRuOSteffens1, Friedt2, Sidis3 et al. 2011Phys. Rev. BSelf Cite

Magnetic excitations in the metallic single-layer ruthenates Ca2−xSrxRuOSteffens1, Friedt2, Sidis3 et al. 2011Phys. Rev. BSelf Cite

Higgs mode and its decay in a two-dimensional antiferromagnet

Observation of two-dimensional spin fluctuations in the bilayer ruthenateSr3Ru2O

Contact Info

Product

Resources

About

Magnetic excitations in the metallic single-layer ruthenates Ca2−xSrxRuO
Steffens
¹
,
Friedt
²
,
Sidis
³

et al. 2011
Phys. Rev. B
Self Cite

Magnetic excitations in the metallic single-layer ruthenates Ca2−xSrxRuO
Steffens
¹
,
Friedt
²
,
Sidis
³

et al. 2011
Phys. Rev. B
Self Cite