Experimental Determination of Anisotropy Fields, First and Second Anisotropy Constants, and Remanent Magnetizations in Self-Polarized Zn–Ti and Co–Ti Equally Co-Substituted BaM Ferrites

M-type hexagonal barium ferrites Ba(
${\text{M}_{x}}$
${\text {Ti}_{x}}$
)Fe12-2xO19 (M = Co or Zn,
$x$
= 0–0.5) were synthesized by the chemical topotactical reaction. Both randomly oriented and self-polarized samples were prepared. Experimental values of the anisotropy fields, first and second anisotropy constants, and remanent magnetizations were extracted by combining hysteresis loops and microwave measurements. A salient result of this study is that, compared with
$K_{1}$
,
$K_{2}$
cannot be disregarded for these co-doped BaM hexaferrites, even at low doping levels. Results show that the BaM ferrites of composition Ba(Cox
${\text {Ti}_{x}}$
)Fe12-2xO19 are more suitable for microwave applications that operate at frequencies between 30 and 40 GHz.