Point-Contact Spectroscopy Study of the Ferromagnetic Superconductor ZrZn$_2$

Superconductivity and ferromagnetism are competing orders, but in ZrZn$_2$ evidence for superconductivity has been observed in the ferromagnetic state [1]. We have performed point-contact spectroscopy measurements on single-crystal samples of ZrZn$_2$ using Au and Pt-Ir tips. We present differential conductance spectra measured down to 100 mK, along with their magnetic-field evolution. Implications of our data on possible pairing symmetry [2] and pairing mechanism [3] will be discussed. *Permanent address: Inst. Surface Chemistry, N.A.S. Ukraine, Kyiv, Ukraine. [1] C. Pfleiderer et al. Nature \textbf{412,} 58 (2001). [2] M.B. Walker and K.V. Samokhin, Phys. Rev. Lett. \textbf{88,} 207001 (2002). [3] D.J. Singh and I.I. Mazin Phys. Rev. Lett. \textbf{88,} 187004 (2002).