Equiatomic PtMn layers have been grown epitaxially on Si (001), with the face-centered tetragonal L1(0)-ordered antiferromagnetic phase forming without post-growth magnetic field annealing. The thickness dependence of the exchange anisotropy field and coercivity of the NiFe ferromagnetic layer in the epitaxial PtMn/NiFe exchange-coupled bilayers showed the critical thickness of the PtMn to be 10 nm. The exchange biasing properties are stabilised above a PtMn thickness of 15 nm which is much lower than that for polycrystalline PtMn-based exchange-biased systems. The highest value of exchange-bias is observed for a NiFe ferromagnetic layer thickness of 6 nm. The temperature dependence of the magnetic properties in the range 50-400 K shows that H-ex and H-c increase monotonically in a quasi-linear manner as temperature decreases. Non-saturation of the in-plane magnetisation component of the PtMn, due to the Neel axis lying normal to the interface, is suggested to be responsible for the temperature dependence. (c) 2005 Elsevier B.V. All rights reserved.