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- ItemGradual pressure-induced enhancement of magnon excitations in CeCoSi(Woodbury, NY : Inst., 2020) Nikitin, S.E.; Franco, D.G.; Kwon, J.; Bewley, R.; Podlesnyak, A.; Hoser, A.; Koza, M.M.; Geibel, C.; Stockert, O.CeCoSi is an intermetallic antiferromagnet with a very unusual temperature-pressure phase diagram: At ambient pressure it orders below TN=8.8K, while application of hydrostatic pressure induces a new magnetically ordered phase with exceptionally high transition temperature of ∼40K at 1.5 GPa. We studied the magnetic properties and the pressure-induced magnetic phase of CeCoSi by means of elastic and inelastic neutron scattering (INS) and heat capacity measurements. At ambient pressure CeCoSi orders into a simple commensurate AFM structure with a reduced ordered moment of only mCe=0.37(6)μB. Specific heat and low-energy INS indicate a significant gap in the low-energy magnon excitation spectrum in the antiferromagnetic phase, with the CEF excitations located above 10 meV. Hydrostatic pressure gradually shifts the energy of the magnon band towards higher energies and the temperature dependence of the magnons measured at 1.5 GPa is consistent with the phase diagram. Moreover, the CEF excitations are also drastically modified under pressure. © 2020 authors.
- ItemMagnetic-field- and temperature-dependent fermi surface of CeBiPt(Milton Park : Taylor & Francis, 2006) Wosnitza, J.; Goll, G.; Bianchi, A.D.; Bergk, B.; Kozlova, N.; Opahle, I.; Elgazzar, S.; Richter, Manuel; Stockert, O.; Löhneysen, H.V.; Yoshino, T.; Takabatake, T.The half-Heusler compounds CeBiPt and LaBiPt are semimetals with very low charge-carrier concentrations as evidenced by Shubnikov–de Haas (SdH) and Hall-effect measurements. Neutron-scattering results reveal a simple antiferromagnetic structure in CeBiPt below TN = 1.15 K. The band structure of CeBiPt sensitively depends on temperature, magnetic field and stoichiometry. Above a certain, sample-dependent, threshold field (B>25 T), the SdH signal disappears and the Hall coefficient reduces significantly. These effects are absent in the non-4f compound LaBiPt. Electronic-band-structure calculations can well explain the observed behaviour by a 4f-polarization-induced Fermi-surface modification.