Two- and three-dimensional magnetic correlations in the spin-12square-lattice systemZn2VO

Abstract

The magnetic correlations in the quasi-two dimensional spin-1/2 square-lattice system Zn 2 VO(PO 4 ) 2 have been investigated by neutron diffraction technique. A long-range antiferromagnetic (AFM) ordering below 3.75 K (T N ) has been observed with a reduced moment of 0.66(2) μ B per V ion at 1.5 K. In a given ab plane, the AFM spin arrangement is Néel type and the AFM layers are coupled ferromagnetically along the c axis. Remarkably, we have observed a pure 2D short-range AFM ordering in the ab plane above T N . Interestingly, the coexistence of diffuse magnetic scattering and three dimensional antiferromagnetic Bragg peaks has been found below T N , indicating the presence of spin-waves as confirmed by our calculation using the linear spin-wave theory. The observed results are discussed in the light of existing theory for a two-dimensional spin-1/2 square-lattice system.

Low-temperature nuclear magnetic resonance investigation of systems frustrated by competing exchange interactions

“…3.4. Our spectra are, therefore, consistent with the collinear magnetic order determined from the neutron diffraction experiments [106].…”

“…We fitted the temperature dependence of K iso above 6 K by eqn. 3.1 where [105] and neutron diffraction experiments [106]. The total hyperfine coupling constant at the P site is the sum of transferred hyperfine (A trans ) and dipolar (A dip ) couplings produced by V 4+ spins, i.e., A hf = z A trans + A dip , where z is the number of nearest-neighbor V 4+ spins of the P site.…”

“…From neutron scattering data [106], the J ⊥ is estimated to be around -0.2 K, which is small but not negligible and which is responsible for the long-range ordering (LRO) in this systems below T N ≈ 3.7 K. In this following section we present results of 31 P-NMR study done on Zn 2 VO(PO 4 ) 2 to further invesitigate its ground state and the spin dynamics.…”

“…Neutron diffraction study [106] has shown that below T N ≈ 3.75 K, while along the ab-plane the magnetic ordering is Néel type antiferromagnetic (AFM), along the c-direction the ordering is ferromagnetic(FM). From the density-functional-theory(DFT)-based calculations also Zn 2 VO(PO 4 ) 2 is evidenced to have a spin-1/2 AFM square lattice model [107].…”

Magnetic correlation in the square-lattice spin system (CuBr)Sr2Nb3O10: A neutron diffraction study

“…23,24 The square-lattice layered vanadium phosphate AA VO(PO 4 ) 2 with AA = Zn 2 also reveals AFM J 1 and J 2 . 25,26 On the other hand, the other layered vanadium phosphates AA VO(PO 4 ) 2 with AA = Pb 2 , 27 BaZn, 28 SrZn, 29 and BaCd 30 (with square-lattice spin arrangements) show the FM J 1 and AFM J 2 . A recent investigation shows that PbZnVO(PO 4 ) 2 also belongs to the square-lattice compound with FM J 1 and AFM J 2 .…”