General features of latent track formation in magnetic insulators irradiated with swift heavy ions

A thermal spike model is proposed for the analysis of latent track formation in insulators. The model predicts that above a threshold electronic stopping power ${\mathit{S}}_{\mathit{e}\mathit{t}}$ ${\mathit{R}}_{\mathit{e}}^2$∼ln${\mathit{S}}_{\mathit{e}}$ for 1≤${\mathit{S}}_{\mathit{e}}$/${\mathit{S}}_{\mathit{e}\mathit{t}}$≤2.7 followed by ${\mathit{R}}_{\mathit{e}}^2$∼${\mathit{S}}_{\mathit{e}}$ for 2.7≤${\mathit{S}}_{\mathit{e}}$/${\mathit{S}}_{\mathit{e}\mathit{t}}$ (${\mathit{R}}_{\mathit{e}}$ being the effective track radius). A simple expression is derived for the evaluation of ${\mathit{S}}_{\mathit{e}\mathit{t}}$ from material parameters. A good agreement is found with literature data on latent tracks in magnetic insulators. The analysis showed that the width of the temperature distribution is a(0)=(4.5±0.25) nm and the energy deposited in the spike is 0.17${\mathit{S}}_{\mathit{e}}$.