Epitaxial growth of γ-CoV2O6 thin films: Structure, morphology, and magnetic properties

Abstract

We report on the epitaxial growth of 100 nm thick triclinic γ-CoV2O6 thin films deposited by pulsed laser deposition on TiO2(100) substrate. The layers were grown in narrow experimental conditions, at 600 °C and 0.1 millibar oxygen pressure. X-ray diffraction and transmission electron microscopy evidenced the presence of two variants and the following epitaxial relation between the layers and the substrate: [001]TiO2(100)∥[0±10]γ-CoV2O6(100). Besides the magnetization steps expected in γ-CoV2O6, low temperature magnetic measurements performed along different crystalline axes show the existence of a strong anisotropy compatible with that expected from a one dimensional system, with the easy magnetization axis lying along the b direction (i.e., the Co chains).

Field-Induced Spin-Structural Transition and Giant Magnetostriction in Ising Chain α-CoV2O6

“…Both α-CoV 2 O 6 and γ-CoV 2 O 6 show large single ion anisotropy, undergo long-range AFM transition below 15 and 6 K, respectively and exhibit field-induced metamagnetic transitions at two critical fields H c1 and H c2 . [9][10][11][12][13][14][15][16] The values of magnetic moment determined from the saturation magnetization (M S ) in the fieldinduced FM state and susceptibility in the paramagnetic (PM) state are found to be significantly larger than the expected spin-only moment of high spin-state Co 2+ ion. [9][10][11] In α-CoV 2 O 6 , M S is as much as 1.5 µ B /Co larger than the spin-only moment (3.0 µ B /Co) for H parallel to c axis.…”

“…Recently, the quasi-one-dimensional (1D) spin-chain CoV 2 O 6 has received attention to the scientific community due to the observation of 1/3 magnetization plateau similar to that observed in a regular triangular lattice. [9][10][11][12][13][14][15][16][17][18][19] In monoclinic α-CoV 2 O 6 and triclinic γ-CoV 2 O 6 , the edge-shared CoO 6 octahedra form a magnetic chain along the b axis, and the edge-shared VO 5 square pyramids are located in between the magnetic chains. The much larger Co-Co interchain distance as compared to the intrachain Co-Co distance and the presence of the nonmagnetic V 5+ ion in between the chains weaken the interchain magnetic coupling considerably.…”

“…[9][10][11] Magnetic, electric, and structural properties have been studied extensively to disclose the underlying mechanism responsible for the step-like jumps in M(H) of CoV 2 O 6 . [9][10][11][12][13][14][15][16] Neutron diffraction studies have revealed that these jumps in M(H) curve are coupled to the field-induced magnetic phase transitions from AFM to FM state through an intermediate ferrimagnetic state. [13][14][15] To elucidate the nature of field-induced metamagnetic transition and the thermodynamic properties of frustrated systems, the measurement of specific heat (C p ) in applied field is important.…”

Magnetic and magnetocaloric properties of quasi-one-dimensional Ising spin chain CoV2O6

“…The easy axis is along the c axis in α phase 12,13 while it is along the chain direction in γ phase. 20,21 As V ions are in nonmagnetic pentavalent state, the magnetic contribution comes from the Co 2+ ion. The intrachain magnetic interaction is strong and ferromagnetic in nature while the chains are weakly coupled via antiferromagnetic interaction.…”

Field induced metamagnetic transitions in quasi-one-dimensional Ising spin chain CoV2O6

“…The easy axis is perpendicular to chain direction in α phase 9,10 while it is pointing along the chain direction in γ phase. 17,18 The magnetic properties of CoV 2 O 6 are solely determined by the divalent Co 2+ ions because the V ions are in a nonmagnetic V 5+ state. The Co 2+ ions within the same chain are strongly coupled via ferromagnetic (FM) interaction while the interchain interaction is weak and antiferromagnetic (AFM) in nature.…”