Pressure tuning of competing magnetic interactions in intermetallic CeFe2

Abstract

We use high-pressure magnetic x-ray diffraction and numerical simulation to determine the lowtemperature magnetic phase diagram of stoichiometric CeFe2. Near 1.5 GPa we find a transition from ferromagnetism to antiferromagnetism, accompanied by a rhombohedral distortion of the cubic Laves crystal lattice. By comparing pressure and chemical substitution we find that the phase transition is controlled by a shift of magnetic frustration from the Ce-Ce to the Fe-Fe sub-lattice. Notably the dominant Ce-Fe magnetic interaction, which sets the temperature scale for the onset of long range order, remains satisfied throughout the phase diagram but does not determine the magnetic ground state. Our results illustrate the complexity of a system with multiple, competing magnetic energy scales and lead to a general model for magnetism in cubic Laves phase intermetallic compounds.

Hidden one-dimensional spin modulation in a three-dimensional metal

“…The stability of antiferromagnetic order with large variations in the lattice spacing is unusual and raises fundamental physics and technological questions 20 . Very few examples exist in the P = 0.0 GPa P = 5.6 GPa P = 11.3 GPa Figure 4 | Evolution of the nesting band under pressure.…”

“…A NaI detector was used for measuring X-ray intensity, but no polarization analyser was used for magnetically diffracted X-rays. Using a six-circle Huber c-diffractometer in the vertical diffraction geometry, a high resolution in momentum space better than 1 Â 10 À 3 Å À 1 FWHM is achieved for longitudinal scans 11,20,21 . All measurements were made at the base temperature of the cryostat, which varied between 3.5 and 5.5 K for various cooldowns.…”

“…Non-resonant X-ray magnetic diffraction under pressure was performed at beamline 4-ID-D of the Advanced Photon Source 19,20 . A focused 20,000 keV X-ray beam was reduced to 100 Â 100 mm 2 size by motorized slits to match typical sample sizes around 80 Â 80 Â 30 mm 3 under pressure.…”

“…The typical pressure range for neutron magnetic diffraction is 25 GPa for powders 16 and o10 GPa for single crystals 17 . Single-crystal X-ray magnetic diffraction has become competitive over the past decade as a direct probe of antiferromagnetism under pressure [18][19][20] .…”

High-resolution neutron depolarization microscopy of the ferromagnetic transitions in Ni3Al and HgCr2Se4 under pressure

“…To alleviate these difficulties, we demonstrate a new method of spatiallyresolved thermodynamic measurements of magnetic phase transitions and demonstrate inhomogeneities and domain formation near the transition temperature in Ni 3 Al and HgCr 2 Se 4 , two well-known examples of materials affected by the proximity to a QCP. Ni 3 Al is an archetypical weak itinerant ferromagnet [18,19]. Due to it's proximity to a QCP, the Curie temperature of Ni 3 Al has strong compositional dependence [20].…”