Physical properties of CeIrSi with trillium-lattice frustrated magnetism

Magnetic $(\ensuremath{\chi})$, transport $(\ensuremath{\rho})$, and heat capacity $({C}_{\mathrm{m}})$ properties of CeIrSi are investigated to elucidate the effect of geometric frustration in this compound with trillium type structure because, notwithstanding its robust effective moment, ${\ensuremath{\mu}}_{\mathrm{eff}}\ensuremath{\approx}2.46\phantom{\rule{4pt}{0ex}}{\ensuremath{\mu}}_{\mathrm{B}}$, this Ce-lattice compound does not undergo a magnetic transition. In spite of that it shows broad ${C}_{\mathrm{m}}(T)/T$ and $\ensuremath{\chi}(T)$ maxima centered at ${T}_{\mathrm{max}}\ensuremath{\approx}1.5$ K, while a $\ensuremath{\rho}\ensuremath{\propto}{T}²$ thermal dependence, characteristic of electronic spin coherent fluctuations, is observed below ${T}_{\mathrm{coh}}\ensuremath{\approx}2.5$ K. Magnetic field does not affect significantly the position of the mentioned maxima up to $\ensuremath{\approx}1$ T, though $\ensuremath{\chi}(T)$ shows an incipient structure that completely vanishes at ${\ensuremath{\mu}}₀H\ensuremath{\approx}1$ T. Concerning the $\ensuremath{\rho}\ensuremath{\propto}{T}²$ dependence, it is practically not affected by magnetic field up to ${\ensuremath{\mu}}₀H=9$ T, with the residual resistivity ${\ensuremath{\rho}}₀(H)$ slightly decreasing and ${T}_{\mathrm{coh}}(H)$ increasing. These results are compared with the physical properties observed in other frustrated intermetallic compounds.