| Publisher Information: |
Uppsala universitet, Materialteori; Uppsala universitet, Institutionen för fysik och astronomi; Stockholm Univ, Dept Chem, SE-10691 Stockholm, Sweden.;KTH Royal Inst Technol, Dept Appl Phys, SE-10691 Stockholm, Sweden.; Natl Inst Mat Sci, Tsukuba, Ibaraki 3050044, Japan.; Univ Zurich, Phys Inst, Winterthurerstr 190, CH-8057 Zurich, Switzerland.; Chalmers Univ Technol, Dept Phys, SE-41296 Gothenburg, Sweden.; Uppsala Univ, Dept Phys & Astron, Box 516, SE-75120 Uppsala, Sweden.; Babes Bolyai Univ, Fac Phys, Cluj Napoca 3400, Romania.; PSI Ctr Neutron & Muon Sci CNM, CH-5232 Villigen, Switzerland.; Ehime Univ, Geodynam Res Ctr, PIAS, Matsuyama 7908577, Japan.; SPring 8, Japan Synchrotron Radiat Res Inst, 1-1-1 Kouto, Sayo, Hyogo 6795198, Japan.; Rutherford Appleton Lab, ISIS Neutron & Muon Source, Didcot OX11 0QX, England.;Univ Edinburgh, EaSTChem Sch Chem, Kings Bldg,West Mains Rd, Edinburgh EH9 3FJ, Scotland.; Rutherford Appleton Lab, ISIS Neutron & Muon Source, Didcot OX11 0QX, England.; Comprehens Res Org Sci & Soc CROSS, Neutron Sci & Technol Ctr, Tokai, Ibaraki 3191106, Japan.; KEK, Inst Mat Struct Sci, Muon Sci Lab, Tokai, Ibaraki 3191106, Japan.; KTH Royal Inst Technol, Dept Appl Phys, SE-10691 Stockholm, Sweden. |
| Description: |
We investigate the pressure-dependent magnetism of the quasi-one-dimensional solid solution Ca1-xNaxCr2O4 using neutron diffraction, Cr K-edge x-ray absorption spectroscopy, and muon spin rotation/relaxation. Na substitution is known to increase oxygen-ligand hole density (partial Cr3+ to Cr4+ character) and to drive the evolution from incommensurate order in CaCr2O4 to commensurate antiferromagnetism in NaCr2O4, suggesting a complex interplay between charge doping and structural changes. Here we apply hydrostatic pressure to tune the lattice without altering the nominal hole count, thereby separating compression effects from ligandhole physics. For x = 0 and x = 0.5 the magnetic transition temperature is essentially pressure independent within our explored range, whereas in NaCr2O4 long-range order is progressively suppressed with pressure, as seen by a decrease of TN and of the magnetic Bragg intensity. Over the same pressure range, Cr K-edge x-ray absorption spectroscopy shows no resolvable change in the average Cr valence or coordination, and the refined corner-sharing Cr-O-Cr geometry remains nearly invariant within uncertainty. Extrapolating the pressure dependence of the magnetic order parameter suggests a critical pressure Pc = 107(8) kbar for complete suppression of long-range order. These results support ligand-hole density as the primary control parameter across Ca1-xNaxCr2O4, with pressure acting as a secondary electronic tuning knob that weakens ordering in the Na-rich end member without inducing a new magnetic phase. |