Magnetic properties of disordered oxides with iron and manganese ions

Preparation and magnetic properties of amorphous EuTiO3 thin films

“…Spin glass (SG)-like magnetic transition of oxide and fluoride glasses has been extensively investigated so far [1][2][3][4][5][6]. In most insulating oxide and fluoride glasses, short-range antiferromagnetic (AFM) superexchange interactions via anions are dominant, as demonstrated by the negative values of Weiss temperature (θ W ) [4][5][6]. The random distribution of magnetic ions, as well as the prevailing AFM interactions among magnetic ions, causes geometrical frustration in the alignment of magnetic moments at low temperatures, eventually leading to the SG transition.…”

Spin dynamics in oxide glass of Fe2O3–Bi2O3–B2O3 system

“…Several investigators reported that oxide glasses containing a large amount of magnetic ions show magnetic transitions as observed in spin glasses or superparamagnets [9][10][11]. Nonetheless, experiments have been little performed to clarify completely the mechanism of magnetic transition as well as the characteristics of magnetically ordered phase for those glasses derived from ionic compounds.…”

Magnetic properties of oxide glasses containing iron and rare-earth ions

“…1 Instead, short-range antiferromagnetic (AFM) superexchange interactions via 2p states of oxide ions are predominant in the magnetic oxide glasses, [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] with some exceptions such as Eu 2+ -containing glasses, where ferromagnetic (FM) interactions prevail. [19][20][21][22][23] In a system where magnetic moments are located at randomly distributed cations, the short-range AFM interactions inevitably bring about magnetic frustrations of geometrical origin.…”

“…[2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Those 3d TM-containing glasses have negative Weiss temperatures, the amplitude of which is tens or hundreds of degrees Kelvin, and exhibit a paramagnetic (PM) to SG transition at several or tens of degrees Kelvin. On the other hand, most of the oxide glasses possessing 4f rare-earth (RE) ions seldom show any magnetic transition down to 2 K, 24,25 which can be easily accessed in magnetic measurements.…”