Magnetic properties of Al2O3–Cr2O3 solid solutions

Boundary magnetization properties of epitaxialCr2−xAlxO3thin fi

“…Specifically, we demonstrate the growth of high-quality corundum Cr (2-x) Al (x) O 3 (0001) thin films in the concentration range between x = 0 to x = 0.6, successfully verifying the suitability of the hybrid growth procedure for Chromia-based alloy fabrication, which extends our previous work on high-quality pure α-Cr 2 O 3 thin film growth [12,13]. The samples show a linear variation of the lattice constants a and c with x, as well as a monotonic decrease of the Néel temperature with x similar to the results of studies on bulk polycrystalline alloy samples [19,20,21,22]. In contrast with those studies, the highly oriented epitaxial nature of our alloy film samples allows the use of the boundary magnetization as a probe to study the magnetic transition.…”

“…Both a and c decrease linearly with x, further corroborating the smooth tunability of our highquality growth process. The agreement with lattice constants published for polycrystalline bulk Cr (2-x) Al (x) O 3 alloy samples is very good, as can be seen from the comparison in Table I [ 20,22]. For the purpose of a further sample comparison, Fig.5 shows experimental results of XRD φ-scans for the entire range of alloy compositions investigated here.…”

“…, so that the distance between the lattice planes decreases upon increasing the amount of Alumina in the alloy [22]. Correspondingly, the XRD peak positions in our samples shift from diffraction angles of 39.75° (0006) and 33.6° (10)(11)(12)(13)(14) for the pure Cr 2 O 3, towards the Al 2 O 3 (0006) and (10-14) diffraction peaks upon increasing x.…”

“…α-Al 2 O 3 in its single crystalline form sapphire has been demonstrated to allow for epitaxial growth of Chromia films due to the advantage of structural isomorphism and relatively low lattice mismatch, given that |∆ |/ = 4.0% and |∆ |/ = 4.6% [8,10,12,13,18]. Correspondingly, Cr (2-x) Al (x) O 3 alloy films with (0001) surface orientation are a most suitable test case for the investigation of structural and magnetic properties, especially in terms of the robustness of boundary magnetization, which has been entirely unexplored so far [19,20,21,22]. In this work, we present a detailed study of the structural and magnetic properties of epitaxial Cr (2-x) Al (x) O 3 alloys in the composition range of x = 0 -0.6 .…”

Magnetic field induced switching of the antiferromagnetic order parameter in thin films of magnetoelectric chromia

“…However, only at T >900 °C epitaxial transformation from CrO 3 to the Cr 2 O 3 phase can be achieved for film deposition on top of sapphire substrates [29,30,31,32,33]. Therefore, we thermally annealed our samples after deposition at 1000 °C in vacuum (3 Pa) for 1 h. Fig.1 shows the XRD data for samples of thicknesses d = 26, 50, and 60 nm after the annealing step.…”