Quantum oscillations and transport properties of layered single-crystal <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>SrCu</mml:mi><mml:mn>4</mml:mn></mml:msub><mml:msub><mml:mi>As</mml:mi><mml:mn>2</mml:mn></mm

We report a systematic investigation of the physical properties and Fermi-surface topology of layered single-crystal ${\mathrm{SrCu}}_{4}{\mathrm{As}}_{2}$ using electrical transport, magnetotransport, and quantum-oscillation experiments plus band-structure calculations. The temperature-dependent electrical resistivity reveals a hysteretic phase transition at ${T}_{P}=59$ K, most likely associated with a structural change. Hall resistivity data suggest a marked change in the average hole density resulting from the latter phase transition near ${T}_{P}$. A large, linear, and nonsaturating magnetoresistance is observed at low temperatures in ${\mathrm{SrCu}}_{4}{\mathrm{As}}_{2}$, likely attributable to the multipocket Fermi surface. Quantum-oscillation data measured in magnetic fields of up to 60 T show several oscillation frequencies exhibiting low effective masses, indicating the presence of Dirac-like band dispersion in ${\mathrm{SrCu}}_{4}{\mathrm{As}}_{2}$, as suggested by the band structure calculations.