Dependence of spin Hamiltonian parameters E and D on labeling of magnetic axes: Application to ESR of high-spin Fe3+

Alternative zero-field splitting (ZFS) parameter sets and standardization for Mn2+ ions in various hosts exhibiting orthorhombic site symmetry

“…recognized and discussed [45]. The number of applications of the standardization idea [6][7][8][9][10] has been growing since its comprehensive extensions appeared [20,21]; see the recent papers [22][23][24] and references therein.…”

“…Based on this idea two standardization conventions have been proposed [9,10]. The standard range 0 ≤ λ ≤ 1/3 corresponds [9] in terms of the diagonal components of the conventional ZFS D tensor (S.D.S) [11,12] to ¨D XX¸ ≤ ¸D YY¸ ≤¸D ZZ¸, whereas -1/3 ≤ λ ≤ 0 corresponds [10] to ¸D YY¸ < ¨D XX¸ ≤ ¸D ZZ¸.…”

“…The standard range 0 ≤ λ ≤ 1/3 corresponds [9] in terms of the diagonal components of the conventional ZFS D tensor (S.D.S) [11,12] to ¨D XX¸ ≤ ¸D YY¸ ≤¸D ZZ¸, whereas -1/3 ≤ λ ≤ 0 corresponds [10] to ¸D YY¸ < ¨D XX¸ ≤ ¸D ZZ¸. Hence, the former (later) convention is equivalent to choosing the direction of the maximum overall splitting of an EPR spectrum as the Z axis and that A c c e p t e d m a n u s c r i p t 2 of the minimum as the X axis (Y axis) [13,14,15,16].…”

On standardization of low symmetry crystal fields

“…This time however each S i characterized by appropriate range of κ represents four different sets of parameters. These four sets can be generated from each of them by rotations by π about the two perpendicular coordinate axes -R Oy ( / ) 2 π and R Oz ( / ) 4 π .…”

“…The standardization was introduced originally as a convention for selecting the principal directions in description of zero field splitting observed in EPR spectra [3,4]. It was noticed that six equivalent orientations of the coordinate system in the case of orthorhombic symmetry were related to different ranges of the rhombicity -the ratio of the two parameters describing the quadrupole footprint on the EPR recordings.…”