Top: pressure cell: (1) hardened MP35N pressure cell, (2) x-ray window, (3) thermometer position, (4) MP35N suspension ring, (5) hardened CuBe lock screw, (6) tungsten carbide thrust disk, (7) tungsten carbide piston, (8) Teflon sample holder. Bottom: schematic drawing of pressure cell with sample, pressure calibrant, and external piston. Dimensions in millimeter.
Left: compression of the pressure cell vs load during autofrettage process using a piston with diameter. A Teflon cylinder served as pressure transmitting medium. Right: vs load during the experiment on a single crystal contained in a Teflon cup filled with DAPHNE oil. The Teflon cup also contained a small crystal. Here, a piston with diameter was used.
Intensity vs scattering angle for the powder spectrum of MP35N. The arrows indicate the values of a selection of superlattice reflections of interest in .
Intensity of the (0.5, 3, 0.5) superstructure reflection of vs temperature for different loads. The inset shows the extracted pressure values at low temperature.
Orthorhombic strain vs parameter . As described in detail in Ref. 31, , where , is the temperature of the high-temperature structural transition in , and accounts for the nonlinearity of at low . is the critical pressure in , and the critical Sr content in to suppress the orthorhombic phase. We have used the same parameter values (Ref. 32) as in Ref. 31, except for , which has a slightly smaller , and for , where we have adjusted the Sr content to , to compensate the effect of Nd doping on and . The data for in were taken from Ref. 33, in from Ref. 31, in this work, and in from Ref. 34.
Left: single crystals of (black) and (blue). is used as a pressure calibrant. The red object is a match head (for scale). The black dot below the scale indicates the typical size of a sample that fits into a DAC. Right: pressure dependence of in as determined from ac susceptibility in magnetic fields between 0.1 and (Ref. 39).
Orthorhombic strain at , 1.5, and for various temperatures, as determined from transverse scans through the Bragg peaks. The additional split of the reflections in the orthorhombic phase at and most likely indicates a weak monoclinic distortion, previously observed in (Ref. 46).
Left: scans through the charge stripe order peak at of the crystal (mounted in the pressure cell) at different temperatures. These data are for ambient pressure. All scans, except the one at , are shifted for clarity. A corresponding scan through the nearby (2, 0, 6) Bragg reflection at indicates the instrumental resolution (solid red line). The background signal of the pressure cell is , the sample contributes another to the background. At , the ratio between peak intensity and combined background is about 1:5. Right: normalized integrated intensity of the (2.24, 0, 5.5) charge peak and the (1, 0, 0) LTT peak vs temperature.
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