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We have used high-resolution neutron spectroscopy experiments to determine the complete spin wave spectrum of the heavy-fermion antiferromagnet CeRhIn5. The spin wave dispersion can be quantitatively reproduced with a simple frustrated J1-J2 model that also naturally explains the magnetic spin-spiral ground state of CeRhIn5 and yields a dominant in-plane nearest-neighbor magnetic exchange constant J0 = 0.74(3) meV. Our results pave the way to a quantitative understanding of the rich low-temperature phase diagram of the prominent Ce7In5 (T = Co, Rh, Ir) class of heavy-fermion materials. [ABSTRACT FROM AUTHOR]

Neutron-diffraction and magnetic susceptibility studies of polycrystalline SrCr2As2 reveal that this compound is an itinerant G-type antiferromagnet below the Néel temperature TN = 590(5) K with the Cr magnetic moments aligned along the tetragonal c axis. The system remains tetragonal to the lowest measured temperature (~12 K). The lattice parameter ratio c/a and the magnetic moment saturate at about the same temperature below ~200 K, indicating a possible magnetoelastic coupling. The ordered moment μ=1.9(1)μB/Cr, measured at T=12 K, is significantly reduced compared to its localized value (4μB/Cr) due to the itinerant character brought about by hybridization between the Cr 3d and As 4p orbitals. [ABSTRACT FROM AUTHOR]

We have performed inelastic neutron scattering measurements on powder samples of the quasicrystal approximant, TbCd6, grown using isotopically enriched 112Cd. Both quasielastic scattering and distinct inelastic excitations were observed below 3 meV. The intensity of the quasielastic scattering measured in the paramagnetic phase diverges as TN~22 K is approached from above. The inelastic excitations, and their evolution with temperature, are well characterized by the leading term, B20O20, of the crystal electric field (CEF) level scheme for local pentagonal symmetry for the rare-earth ions [S. Jazbec et al., Phys. Rev. B 93, 054208 (2016)] indicating that the Tb moment is directed primarily along the unique local pseudofivefold axis of the Tsai-type clusters. We also find good agreement between the inverse susceptibility determined from magnetization measurements using a magnetically diluted Tb0.05Y0.95Cd6 sample and that calculated using the CEF level scheme determined from the neutron measurements. [ABSTRACT FROM AUTHOR]

Iron pnictides and related materials have been a topic of intense research for understanding the complex interplay between magnetism and superconductivity. Here we report on the magnetic structure of SrMn 2 As 2 that crystallizes in a trigonal structure ([Formula: see text]) and undergoes an antiferromagnetic (AFM) transition at [Formula: see text] K. The magnetic susceptibility remains nearly constant at temperatures [Formula: see text] with [Formula: see text] whereas it decreases significantly with [Formula: see text]. This shows that the ordered Mn moments lie in the [Formula: see text] plane instead of aligning along the [Formula: see text]-axis as in tetragonal BaMn 2 As 2 . Single-crystal neutron diffraction measurements on SrMn 2 As 2 demonstrate that the Mn moments are ordered in a collinear Néel AFM phase with [Formula: see text] AFM alignment between a moment and all nearest neighbor moments in the basal plane and also perpendicular to it. Moreover, quasi-two-dimensional AFM order is manifested in SrMn 2 As 2 as evident from the temperature dependence of the order parameter.

Purpose: Objective is to evaluate cardiovascular autonomic function in SLE by simple non-invasive tests., Methods: A case control study was carried out involving 18-50 yrs old previously diagnosed SLE patients and same number of age and sex-matched controls. Parasympathetic function was assessed by heart rate (HR) response to Valsalva maneuver, deep breathing and standing. Sympathetic function was evaluated by blood pressure response to standing and sustained hand-grip test (HGT)., Results: There were 50 female SLE patients. They had significantly higher minimum resting HR and diastolic blood pressure (DBP). HR variation with deep breathing, expiratory inspiratory ratio, 30:15 ratio and DBP change in response to HGT were significantly lower inpatients compared to controls. Thirty patients (60%) had at least one abnormal or two borderline test results indicating autonomic impairment of which 27 had parasympathetic dysfunction and 7 had sympathetic dysfunction., Conclusion: Autonomic dysfunction is common in SLE with higher prevalence of parasympathetic impairment.