Appearance of a two-dimensional antiferromagnetic order in quasi-one-dimensional cobalt oxides

Abstract

By means of muon spin rotation and relaxation (µ + SR) techniques, we have investigated the magnetism of quasi one-dimensional (1D) cobalt oxides AEn+2Con+1O3n+3 (AE=Ca, Sr and Ba, n=1, 2, 3, 5 and ∞), in which the 1D CoO3 chain is surrounded by six equally spaced chains forming a triangular lattice in the ab-plane, using polycrystalline samples, from room temperature down to 1.8 K. For the compounds with n=1 -5, transverse field µ + SR experiments showed the existence of a magnetic transition below ∼100 K. The onset temperature of the transition (T on c ) was found to decrease with n; from 100 K for n=1 to 60 K for n=5. A damped muon spin oscillation was observed only in the sample with n=1 (Ca3Co2O6), whereas only a fast relaxation obtained even at 1.8 K in the other three samples. In combination with the results of susceptibility measurements, this indicates that a two-dimensional short-range antiferromagnetic (AF) order appears below T on c for all compounds with n=1 -5; but quasi-static long-range AF order formed only in Ca3Co2O6 , below 25 K. For BaCoO3 (n=∞), as T decreased from 300 K, 1D ferromagnetic (F) order appeared below 53 K, and a sharp 2D AF transition occurred at 15 K.

Spin, charge, and orbital correlations in the one-dimensionalt2g-orbital Hubbard model

“…4 Furthermore, the magnetic behavior of quasi-onedimensional Co oxides A n+2 BЈB n O 3n+3 ͑A = Ca, Sr, Ba, BЈ and B =Co͒ has also attracted much attention. 5 For instance, in the n → ϱ compound BaCoO 3 , face-sharing CoO 6 octahedra form one-dimensional cobalt chains in which the Co 4+ ions are in a low-spin state with S =1/2. It has been reported that there occurs ferromagnetic ͑FM͒ order along the chain below 53 K and a two-dimensional antiferromagnetic ͑AFM͒ transition at 15 K due to interchain AFM interactions.…”

Magnetic properties of one-dimensional compounds (, Sr, Ba; )

“…Recently, we performed muon spin rotation and relaxation (m þ SR) measurements, and revealed that the paramagnetic volume fraction in the sample decreased below 100 K [3][4][5]. Because there were no clear anomalies at around 100 K in the temperature dependence of magnetic susceptibility [6], the results of m þ SR experiments were interpreted to be due to the appearance of a short-range 2D-AF order [3][4][5].Ca 3 Co 2 O 6 corresponds to the end member of a homologous series A nþ2 Co nþ1 O 3nþ3 with A ¼ Ca and n ¼ 1 [7]. A short-range magnetic order was also found for the n ¼ 225 and 1 compounds by the m þ SR techniques, and the onset temperature decreased systematically with increasing n, most likely because the inter-chain distance increased [3][4][5].…”

“…Recently, we performed muon spin rotation and relaxation (m þ SR) measurements, and revealed that the paramagnetic volume fraction in the sample decreased below 100 K [3][4][5]. Because there were no clear anomalies at around 100 K in the temperature dependence of magnetic susceptibility [6], the results of m þ SR experiments were interpreted to be due to the appearance of a short-range 2D-AF order [3][4][5].…”

“…Because there were no clear anomalies at around 100 K in the temperature dependence of magnetic susceptibility [6], the results of m þ SR experiments were interpreted to be due to the appearance of a short-range 2D-AF order [3][4][5].…”

Magnetic Spin Correlations in the One-dimensional Frustrated Spin-chain System Ca3Co2O6

“…1(a). Ca 3 Co 2 O 6 is often described as a realization of an Ising model on a triangular lattice and this compound display a smörgåsbord of competing interactions and exotic magnetic phases [3][4][5][6][7]. At low-temperatures (T < T N = 25 K) the system clearly display a long-range antiferromagnetic (AF) order with magnetic Bragg peaks in neutron diffraction measurements [4].…”