Figure 4. Magnetic phase diagram and specific heat data of Sr₂Ru_1−x(Co/Mn)_xO₄.

(a) Magnetic phase diagram; PM: paramagnetic, FM CG: ferromagnetic cluster glass, SG-IC: spin glass state with short-range incommensurate antiferromagnetic order. (b) Doping dependence of Sommerfeld coefficient γ_e. (c) Specific heat C divided by temperature vs. T² for undoped, 1.5% Co-, 3% Mn- and 10% Mn-doped samples. The solid lines represent linear fits. (d) Specific heat C divided by temperature vs. T² for the 0.8% Co-doped sample; the best linear fit (i.e. the solid line) is obtained in the 7–12 K temperature range.