Evolution on magnetic states in frustrated diamond lattice antiferromagnetic Co(AI_1-xCo_x)₂O₄ spinels

TY - JOUR

T1 - Evolution on magnetic states in frustrated diamond lattice antiferromagnetic Co(AI1-xCox)2O4 spinels

AU - Zaharko, O.

AU - Cervellino, A.

AU - Tsurkan, V.

AU - Christensen, N.B.

AU - Loídl, A.

PY - 2010/2/17

Y1 - 2010/2/17

N2 - Using neutron powder diffraction and Monte Carlo simulations we show that a spin-liquid regime emerges at all compositions in the diamond-lattice antiferromagnets Co (Al1-x Cox) 2 O4. This spin-liquid regime induced by frustration due to the second-neighbor exchange coupling J2 is gradually superseded by antiferromagnetic collinear long-range order (k=0) at low temperatures. Upon substitution of Al3+ by Co3+ in the octahedral B site the temperature range occupied by the spin-liquid regime narrows and TN increases. To explain the experimental observations we considered magnetic anisotropy D or third-neighbor exchange coupling J3 as degeneracy-breaking perturbations. We conclude that Co (Al1-x Cox) 2 O4 is below the theoretical critical point J2 / J1 =1/8, and that magnetic anisotropy assists in selecting a collinear long-range ordered ground state, which becomes more stable with increasing x due to a higher efficiency of O-Co3+ -O as an interaction path compared to O-Al3+ -O.

AB - Using neutron powder diffraction and Monte Carlo simulations we show that a spin-liquid regime emerges at all compositions in the diamond-lattice antiferromagnets Co (Al1-x Cox) 2 O4. This spin-liquid regime induced by frustration due to the second-neighbor exchange coupling J2 is gradually superseded by antiferromagnetic collinear long-range order (k=0) at low temperatures. Upon substitution of Al3+ by Co3+ in the octahedral B site the temperature range occupied by the spin-liquid regime narrows and TN increases. To explain the experimental observations we considered magnetic anisotropy D or third-neighbor exchange coupling J3 as degeneracy-breaking perturbations. We conclude that Co (Al1-x Cox) 2 O4 is below the theoretical critical point J2 / J1 =1/8, and that magnetic anisotropy assists in selecting a collinear long-range ordered ground state, which becomes more stable with increasing x due to a higher efficiency of O-Co3+ -O as an interaction path compared to O-Al3+ -O.

U2 - 10.1103/PhysRevB.81.064416

DO - 10.1103/PhysRevB.81.064416

M3 - Journal article

SN - 2469-9950

VL - 81

SP - 064416

JO - Physical Review B

JF - Physical Review B

IS - 6

ER -