Transition from quasi-one-dimensional to spin-glass behaviour in insulating FeMg2BO5

Ludwigites: From natural mineral to modern solid solutions

“…The general chemical formula is Me +3 Mе +2 2 BO 5 . Metal ions can be present as one ion with a different valence (homometallic) , and various ions (heterometallic) . Metal ions (bivalent ‐ Mg, Ni, Zn, Co, Fe, trivalent ‐ Al, V, Cr, Mn, Fe, Ga, Co, tetravalent ‐ Mn, Sn, Ge, Zr, Ti, and even pentavalent ‐ Sb, Nb) are located in the center of the oxygen octahedral coordination with common edges.…”

“…Natural mineral Mg2FeBO5 is the ancestor of the ludwigites family and received its name in honor of Ernst Ludwig, the first who analyzed this mineral in 1874. In modern times, this compound is also actively investigated, the results are given in .…”

“…Ludwigite Mg 2 FeBO 5 contains only one magnetic ion ‐ Fe 3+ , which occupies position 4 and forms linear chains separated from each other by nonmagnetic Mg 2+ ions. These chains can be viewed as a quasi‐one‐dimensional Heisenberg system with a strong short intra‐sublattice antiferromagnetic superexchange interactions (∼ −15 K ) in which a local short‐range antiferromagnetic ordering of spins progressively appears.…”

Reentrant superspin glass state and magnetization steps in the oxyborate Co2AlBO5

“…[7][8][9] The other type comprises of systems in which M is non-magnetic (for instance, Ga, Al, Mg, or Ti), and the resultant dilution of the magnetic lattice typically manifests itself in the form of a reduced transition temperature. [10][11][12][13] Since the M ions has four in-equivalent crystallographic sites within the Ludwigite structure, the eventual properties are likely to be crucially influenced by the occupancies of the different M and M species within these sites. In some Ludwigites, this is also reported to give rise to a low temperature spin glass like state without long range order.…”

“…In some Ludwigites, this is also reported to give rise to a low temperature spin glass like state without long range order. 11,13 A defining feature of the Ludwigite structure is the presence of a zig-zag wall made up of edge sharing octahedra which propagate along the crystallographic c axis ( Figure 1). The four possible crystallographic positions of the M ion are thus distinguished by their positions within these zig-zag structures.…”