Tetramethylammonium Copper Chloride andtris(Trimethylammonium) Copper Chloride:S=12Heisenberg One-Dimensional Ferromagnets

Abstract

The magnetic susceptibilities of powdered samples of Me4NCuCl3 (TMCuC) and [(CH3)3NH]3Cu2Cl7 (TTMCuC) have been measured. Both compounds behave like one-dimensional 5 = 4 Heisenberg ferromagnets which are weakly coupled antiferromagnetically to adjacent chains. For TMCuC, we obtained J/k^ 30 K with \J'\^0.003 K; the ratio |«/V«/| is the lowest yet found for a ferromagnetic 5 = J chain. For TTMCuC, we obtained Jj^yi/k^^O K, with \J' /J^y^\%l(i'^, and ^/AFMA^^-1^ K for the antiferromagnetic chains also present.The magnetic properties of low-dimensional materials continue to be of much interest to physicists and chemists.^ Of the many possible combinations of space dimensionality, spin dimensionality, and spin quantum number, one combination which has been conspicuous by the lack of suitable realizations is the one-dimensional (ID) spin-i Heisenberg ferromagneto The majority of studies on one-dimensional magnetic systems have been on antiferromagnets, with emphasis on S = | Heisenberg (Mn^^-), S^i Ising (Co^"'), and S=i Heisenberg (Cu^^) systems. The general lack of one-dimensional ferromagnets, particularly for S=i where quantum effects are expected to be most pronounced, has been unfortunate. Recently we reported two pseudo-one-dimen-sional ferromagnets ,2 CuClg'DMSO [DMSO = (CH3)2SO] and CuClg» TMSO [TMSO= C4H8SO] with a strong intrachain coupling, 2J/k, of '^ 80-90°K but the extent of interchain coupling (UV^l ^ 10"^) was large enough to preclude their study as ideal systemSo The structural insight gained in these studies prompted us to investigate two additional compounds where the interchain coupling, J', could be expected to be minimized.The results presented in this paper indicate that (CH3)4NCuCl3 (TMCuC) is the most one-dimensional S = i Heisenberg linear chain ferromagnet yet reported. The other compound discussed here, [(CH3)3NH]3Cu2Cl7 (TTMCuC), contains a similar set of linear (CuClg)^ chains with ferromagnetic interactions and very small inter-

Thermodynamics of Heisenberg ferromagnets with arbitrary spin in a magnetic field

“…3 Determining the exchange energy J by a least-squares fit of the theory for S = 1/2 to the experimental data for the magnetization as a function of the magnetic field H at T = 4.1K, 2 we obtain J = 6.18meV and a very good agreement with experiments, as can be seen in the inset of , for H 4kOe. In Fig.…”

Finite-sized Heisenberg chains and magnetism of one-dimensional metal systems

“…7 we report the site dependence of the average easy-axis spin projection S z i in the presence of an applied field B z = 2 T at T = 45 K. The profiles obtained for segments of different lengths N are compared with the expectation value of the infinite chain [50]. Translational invariance is broken for any segment except for the FIGURE 7 The site dependence of S z i is shown for different lengths of the segments at T = 45 K. The site index is enumerated starting from the middle of each segment (the convention of the correlation function is not followed). The dashed line corresponds to the infinite-chain expectation value infinite chain, and S z i decreases symmetrically with respect to the middle of the segment while moving towards the end spins.…”

“…In the well-known cases of the Heisenberg and Ising models, the thermodynamic behavior of a one-dimensional (1D) spin chain of infinite length is characterized by the absence of long-range magnetic order at any non-zero temperature [1][2][3]. In the past, quasi-1D inorganic crystals have been traditionally investigated as 1D Heisenberg model systems [4,5]; typical examples include tetramethylammonium copper and manganese chloride compounds, where Cu 2+ and Mn 2+ ions couple ferromagnetically or antiferromagnetically, respectively, along weakly interacting linear chains separated by intervening non-magnetic complexes [6][7][8]. More recently, the synthesis of molecular ferriand ferromagnetic chain-like compounds containing magnetically anisotropic ions has allowed to realize 1D Ising model systems where the known absence of permanent magnetic order is accompanied by a slow relaxation of the magnetization [9][10][11][12], as predicted by Glauber more than 40 years ago [13].…”

Magnetic structure of quasi-one-dimensional antiferromagnetic TaFe1+yTe3

“…Low dimensional magnetism, particularly in onedimensional systems, has been the subject of intense research interest in the past decades. Even though most materials studied so far have antiferromagnetic exchange interaction along the chain direction, materials with ferromagnetic spin chains, such as LaCrOS 2 [33], CaVO 3 [34], CsNiF 3 [35], CoNb 2 O 6 [36], and some organic materials [37,38], have also been found to have interesting physics. The examples include magnetic soliton like behavior found in CsNiF 3 [35] and the recently-discovered continuous quantum phase transition tuned by external magnetic fields in CoNb 2 O 6 [36].…”