We report the evolution of magnetic phase diagram (
T
,
H
), by accounting for the successive magnetic phase transitions in β-Mn-type Co7Zn7Mn6, a chiral magnet by an elaborate AC susceptibility magnetometry, χ(T, H). The
T
−
H
phase diagram of polycrystalline Co7Zn7Mn6 helimagnet reveals two distinct equilibrium skyrmion phases driven by fluctuations; conventional skyrmion phase (SkX) with helical ordering just below
T
C
∼ 215 K and disordered skyrmion phase (DSkX) just above spin-glass region. The topological nature of SkX is due to high (
↑↑
) spins moment and magnetic disorder driven weak pinning effect manifesting into the stabilization of robust meta-stable skyrmion phase (MSkX) by trivial field-cooling via SkX at
T
S
k
X
M
= 110 K and 150 K. We performed first-principles based density functional theory based calculations, which corroborate with the experimental structural and magnetic ground state of skyrmion-host Co7Zn7Mn6 chiral magnet.
We report detailed magnetization and ac susceptibility studies on a chiral cubic β-Mn type Co8Zn8Mn4 alloy near the onset of magnetic ordering temperature. The Co8Zn8Mn4 alloy undergoes a complex series of temperature-driven transition from paramagnetic to helimagnetic phase through an intermediate inhomogeneous chiral fluctuations phase. The Gaussian shaped peak in χ′(T, H = 0 Oe) at THM ∼= 343.19 K is analogous to that of the zero-field transition to long-period modulated helical state. Moreover, a pronounced field-induced anomaly in χ′(T, H ≥ 500 Oe) rises quickly with field above THMlike a fingerprint, evident of a field-induced crossover into a precursor region. The in-field critical behaviour characterizing a ferromagneticparamagnetic phase transition in the vicinity of ordering temperature confirms that Co8Zn8Mn4chiral magnet belongs to the 3D-Heisenberg universality class. The existence of precursor region and the sizable expansion in the transition temperature, TC can be explained by the Landau equation.
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