Observation of a high-field anomaly in the low-temperature specific heat ofCeCu2Si2

We have performed high-magnetic-field, to 16 T, low-temperature specific-heat measurements for ${\mathrm{CeCu}}_{2.2}$ ${\mathrm{Si}}_2$, ${\mathrm{CeCu}}_2$ ${\mathrm{Si}}_2$, and ${\mathrm{CeCu}}_{1.9}$ ${\mathrm{Si}}_2$. The first two materials, which are superconducting, exhibit a pronounced structure in C/T at T∼0.6 K and H≥10 T. Changing the field from 10 to 16 T does not affect the anomaly. The nonsuperconducting, ${\mathrm{CeCu}}_{1.9}$ ${\mathrm{Si}}_2$, sample does not exhibit a similar anomaly in the investigated temperature range, 0.32–1 K. Possible correlations between this structure and the low-temperature, high-field phase diagram of ${\mathrm{CeCu}}_2$ ${\mathrm{Si}}_2$ are discussed.