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"Cuoco, M."
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Unveiling unconventional magnetism at the surface of Sr2RuO4
2021
Materials with strongly correlated electrons often exhibit interesting physical properties. An example of these materials is the layered oxide perovskite Sr
2
RuO
4
, which has been intensively investigated due to its unusual properties. Whilst the debate on the symmetry of the superconducting state in Sr
2
RuO
4
is still ongoing, a deeper understanding of the Sr
2
RuO
4
normal state appears crucial as this is the background in which electron pairing occurs. Here, by using low-energy muon spin spectroscopy we discover the existence of surface magnetism in Sr
2
RuO
4
in its normal state. We detect static weak dipolar fields yet manifesting at an onset temperature higher than 50 K. We ascribe this unconventional magnetism to orbital loop currents forming at the reconstructed Sr
2
RuO
4
surface. Our observations set a reference for the discovery of the same magnetic phase in other materials and unveil an electronic ordering mechanism that can influence electron pairing with broken time reversal symmetry.
Strontium Ruthenate, Sr
2
RuO
4
, displays a remarkable number of intriguing physical phenomena, from superconductivity, to strain-induced ferromagnetism. Here, using low-energy muon spectroscopy, Fittipaldi et al. demonstrate the existence of unconventional magnetism at the surface of Sr
2
RuO
4
in its normal state and without any applied strain.
Journal Article
Nodal superconducting exchange coupling
2019
A superconducting spin valve consists of a thin-film superconductor between two ferromagnetic layers. A change of magnetization alignment shifts the superconducting transition temperature (ΔΤc) due to an interplay between the magnetic exchange energy and the superconducting condensate. The magnitude of ΔΤc scales inversely with the superconductor thickness (dS) and is zero when dS exceeds the superconducting coherence length (ξ). Here, we report a superconducting spin-valve effect involving a different underlying mechanism in which magnetization alignment and ΔΤc are determined by nodal quasiparticle excitation states on the Fermi surface of the d-wave superconductor YBa2Cu3O7–δ sandwiched between insulating layers of ferromagnetic Pr0.8Ca0.2MnO3. We observe ΔΤc values that approach 2 K with the sign of ΔΤc oscillating with dS over a length scale exceeding 100ξ and, for particular values of dS, the superconducting state reinforces an antiparallel magnetization alignment. These results pave the way to all-oxide superconducting memory in which superconductivity modulates the magnetic state.
Journal Article
Guiding antiferromagnetic transitions in Ca $$_{2}$$ 2 RuO $$_{4}$$ 4
2022
Abstract Understanding and controlling the transition between antiferromagnetic states having different symmetry content with respect to time-inversion and space-group operations are fundamental challenges for the design of magnetic phases with topologically nontrivial character. Here, we consider a paradigmatic antiferromagnetic oxide insulator, Ca $$_{2}$$ 2 RuO $$_{4}$$ 4 , with symmetrically distinct magnetic ground states and unveil a novel path to guide the transition between them. The magnetic changeover results from structural and orbital reconstruction at the transition metal site that in turn arise as a consequence of substitutional doping. By means of resonant X-ray diffraction we track the evolution of the structural, magnetic, and orbital degrees of freedom for Mn doped Ca $$_{2}$$ 2 RuO $$_{4}$$ 4 to demonstrate the mechanisms which drive the antiferromagnetic transition. While our analysis focuses on a specific case of substitution, we show that any perturbation that can impact in a similar way on the crystal structure, by reconstructing the induced spin–orbital exchange, is able to drive the antiferromagnetic reorganization.
Journal Article
Guiding antiferromagnetic transitions in Ca2RuO4
by
Vecchione, A.
,
Forte, F.
,
Porter, D. G.
in
639/766/119/2795
,
639/766/119/995
,
639/766/119/997
2022
Understanding and controlling the transition between antiferromagnetic states having different symmetry content with respect to time-inversion and space-group operations are fundamental challenges for the design of magnetic phases with topologically nontrivial character. Here, we consider a paradigmatic antiferromagnetic oxide insulator, Ca
2
RuO
4
, with symmetrically distinct magnetic ground states and unveil a novel path to guide the transition between them. The magnetic changeover results from structural and orbital reconstruction at the transition metal site that in turn arise as a consequence of substitutional doping. By means of resonant X-ray diffraction we track the evolution of the structural, magnetic, and orbital degrees of freedom for Mn doped Ca
2
RuO
4
to demonstrate the mechanisms which drive the antiferromagnetic transition. While our analysis focuses on a specific case of substitution, we show that any perturbation that can impact in a similar way on the crystal structure, by reconstructing the induced spin–orbital exchange, is able to drive the antiferromagnetic reorganization.
Journal Article
Spin-Orbital Excitations in Ca2RuO4 Revealed by Resonant Inelastic X-Ray Scattering
2018
The strongly correlated insulatorCa2RuO4is considered as a paradigmatic realization of both spin-orbital physics and a band-Mott insulating phase, characterized by orbitally selective coexistence of a band and a Mott gap. We present a high resolution oxygenK-edge resonant inelastic x-ray scattering study of the antiferromagnetic Mott insulating state ofCa2RuO4. A set of low-energy (about 80 and 400 meV) and high-energy (about 1.3 and 2.2 eV) excitations are reported, which show strong incident light polarization dependence. Our results strongly support a spin-orbit coupled band-Mott scenario and explore in detail the nature of its exotic excitations. Guided by theoretical modeling, we interpret the low-energy excitations as a result of composite spin-orbital excitations. Their nature unveils the intricate interplay of crystal-field splitting and spin-orbit coupling in the band-Mott scenario. The high-energy excitations correspond to intra-atomic singlet-triplet transitions at an energy scale set by Hund’s coupling. Our findings give a unifying picture of the spin and orbital excitations in the band-Mott insulatorCa2RuO4.
Journal Article
Guiding antiferromagnetic transitions in Ca $$_{2}$$ RuO $$_{4}
2022
Understanding and controlling the transition between antiferromagnetic states having different symmetry content with respect to time-inversion and space-group operations are fundamental challenges for the design of magnetic phases with topologically nontrivial character. Here, we consider a paradigmatic antiferromagnetic oxide insulator, Ca$$_{2}$$2 RuO$$_{4}$$4 , with symmetrically distinct magnetic ground states and unveil a novel path to guide the transition between them. The magnetic changeover results from structural and orbital reconstruction at the transition metal site that in turn arise as a consequence of substitutional doping. By means of resonant X-ray diffraction we track the evolution of the structural, magnetic, and orbital degrees of freedom for Mn doped Ca$$_{2}$$2 RuO$$_{4}$$4 to demonstrate the mechanisms which drive the antiferromagnetic transition. While our analysis focuses on a specific case of substitution, we show that any perturbation that can impact in a similar way on the crystal structure, by reconstructing the induced spin–orbital exchange, is able to drive the antiferromagnetic reorganization.
Journal Article
High Muscle Sympathetic Nerve Activity Is Associated With Left Ventricular Dysfunction in Treated Hypertensive Patients
by
Ferreira-Filho, Julio Cesar
,
Krieger, Eduardo Moacyr
,
Bortolotto, Luiz Aparecido
in
Adult
,
Antihypertensive Agents - therapeutic use
,
Baroreflex - physiology
2013
BACKGROUND
The presence of asymptomatic left ventricular diastolic dysfunction (LVDD) in hypertensive patients can be associated with the development of cardiac events. The increase in sympathetic activity may be 1 of the mechanisms that predisposes to this outcome. In this study, we analyzed 2 hypotheses: (i) whether sympathetic activity is higher in the presence of LVDD, independent of blood pressure control and (ii) whether different classes of LVDD have a different effect on sympathetic activity.
METHODS
After analyzing left ventricular function using echo Doppler cardiography, 45 hypertensive patients receiving treatment were allocated into 3 groups: normal function (LV-NF, n = 15), impaired relaxation (LV-IR, n = 15), and pseudonormal or restrictive (LV-P/R, n = 15). An age-, sex-, and body mass index-matched control group of normotensive volunteers (N, n = 14) was included. Muscle sympathetic nerve activity (MSNA), heart rate, and systolic blood pressure variabilities and baroreflex sensitivity were evaluated while the patient was in a supine position.
RESULTS
Blood pressure and antihypertensive drug use were similar among the hypertensive groups. The LV-IR and LV-P/R groups had similar MSNA (33±1 and 32±1 bursts/min, respectively), which was significantly higher than that of the LV-NF and N groups (26±3 and 15±2 bursts/min, respectively). The LV-IR and LV-P/R groups had significantly higher LF-systolic blood pressure variability and significantly lower baroreflex sensitivity compared with the N group.
CONCLUSIONS
The presence of asymptomatic LVDD is associated with increased MSNA, independent of blood pressure control. The sympathetic hyperactivity associated with LVDD is similar in the different patterns of LVDD studied.
Journal Article
Genetic Risk Scores and Wearables for CVD Prevention: Insights from the FItPreV Trial
2025
Introduction Cardiovascular diseases (CVDs) are the leading cause of death worldwide. Despite advances in prevention, a substantial burden remains due to modifiable risk factors. Individuals with metabolic syndrome are at particularly high risk. Personalized strategies, such as polygenic risk scores (PRS) and wearable health devices (WHDs), may enhance prevention efforts. The FItPreV study aims to evaluate the feasibility and preliminary impact of these tools in CVD primary prevention among citizens with metabolic syndrome. ClinicalTrials.gov Id: NCT06911294 Methods FItPreV is a pilot randomized controlled trial conducted in seven general practices in Rome. We completed the enrollment of 116 citizens aged 40-69 years with metabolic syndrome. Participants were randomized into four groups: usual care, digital intervention (WHDs), genetic intervention (PRS), and combined intervention (PRS and WHDs). Follow-up assessments are scheduled at 6 and 12 months. Feasibility indicators include recruitment, attendance rates, physicians’ experience, participants’ perceptions, and self-efficacy. Secondary objectives include preliminary evaluation of changes in lipid profiles and lifestyle behaviors. Results Of the 116 participants enrolled, 70 (54%) have completed the 6-month follow-up. Among them, 85% reported satisfaction with the use of PRS and WHDs, without expressing concerns regarding genetic information. Preliminary data show that 78% found WHDs helpful in improving lifestyle habits. However, 65% of general practitioners reported challenges in integrating these new practices due to limited staff and technological resources. Conclusions Preliminary results from the FItPreV study show good feasibility and high acceptability of PRS and WHDs among citizens with metabolic syndrome. However, structural barriers in primary care must be addressed to enable wider implementation. Final results after follow-up will provide further evidence on clinical outcomes and system integration. Key messages • Personalized tools like PRS and wearables are feasible and well accepted for CVD prevention. • Structural barriers in primary care must be addressed to integrate personalized prevention tools.
Journal Article
Guiding antiferromagnetic transitions in CaFormula: see textRuOFormula: see text
2022
Understanding and controlling the transition between antiferromagnetic states having different symmetry content with respect to time-inversion and space-group operations are fundamental challenges for the design of magnetic phases with topologically nontrivial character. Here, we consider a paradigmatic antiferromagnetic oxide insulator, Ca[Formula: see text]RuO[Formula: see text], with symmetrically distinct magnetic ground states and unveil a novel path to guide the transition between them. The magnetic changeover results from structural and orbital reconstruction at the transition metal site that in turn arise as a consequence of substitutional doping. By means of resonant X-ray diffraction we track the evolution of the structural, magnetic, and orbital degrees of freedom for Mn doped Ca[Formula: see text]RuO[Formula: see text] to demonstrate the mechanisms which drive the antiferromagnetic transition. While our analysis focuses on a specific case of substitution, we show that any perturbation that can impact in a similar way on the crystal structure, by reconstructing the induced spin-orbital exchange, is able to drive the antiferromagnetic reorganization.Understanding and controlling the transition between antiferromagnetic states having different symmetry content with respect to time-inversion and space-group operations are fundamental challenges for the design of magnetic phases with topologically nontrivial character. Here, we consider a paradigmatic antiferromagnetic oxide insulator, Ca[Formula: see text]RuO[Formula: see text], with symmetrically distinct magnetic ground states and unveil a novel path to guide the transition between them. The magnetic changeover results from structural and orbital reconstruction at the transition metal site that in turn arise as a consequence of substitutional doping. By means of resonant X-ray diffraction we track the evolution of the structural, magnetic, and orbital degrees of freedom for Mn doped Ca[Formula: see text]RuO[Formula: see text] to demonstrate the mechanisms which drive the antiferromagnetic transition. While our analysis focuses on a specific case of substitution, we show that any perturbation that can impact in a similar way on the crystal structure, by reconstructing the induced spin-orbital exchange, is able to drive the antiferromagnetic reorganization.
Journal Article
Resolving the orbital character of low-energy excitations in Mott insulator with intermediate spin-orbit coupling
2025
Multi-band Mott insulators with moderate spin-orbit and Hund’s coupling are key reference points for theoretical concept developments of correlated electron systems. The ruthenate Mott insulator Ca
2
RuO
4
has therefore been intensively studied by spectroscopic probes. However, it has been challenging to resolve the fundamental excitations emerging from the hierarchy of electronic energy scales. Here we apply high resolution resonant inelastic x-ray scattering to probe deeper into the low-energy electronic excitations found in Ca
2
RuO
4
. In this fashion, we probe a series of spin-orbital excitations. By taking advantage of enhanced energy resolution, we probe a 40 meV mode through the oxygen
K
-edge. The polarization dependence of this low-energy excitations exposes a distinct orbital nature, originating from the interplay of spin-orbit coupling and octahedral rotations. Additionally, we discuss the role of magnetic correlations to describe the occurrence of excitations with amplitudes which are multiple of a given energy. Such direct determination of relevant electronic energy scales sharpens the target for theory developments of Mott insulators’ orbital degree of freedom.
Spin orbit coupling (SOC) is a feature crucial to many interesting physics phenomena ranging from Mott insulators to topological insulators. Here, the authors use resonant inelastic X-ray scattering to study the low-energy excitations of the Mott insulator, Ca2RuO4, and reveal the orbital character of the magnetic properties of the system.
Journal Article