High-Pressure studies on the quasi-one-dimensional heavy fermion metal YbNi${}_4$P${}_2$

YbNi${}_4$P${}_2$ is very unique system among correlated electron compounds due to the quasi-one-dimensional nature. The crystal structure is tetragonal ZrFe${}_4$Si${}_2$ type structure (P4${}_2$/mnm) in which Yb chains along c-axis are separated by chains of edge-shared Ni tetrahedra. Below 0.17K, YbNi${}_4$P${}_2$ orders ferromagnetically (FM) with small ordered magnetic moment of 0.05 ${\mu }_B$. YbNi${}_4$P${}_2$ is a rare expample where a ferromagnetic quantum critical point can be accessed. Here, we present high-pressure studies of YbNi${}_4$P${}_2$ using a diamond-anvil pressure cell. Application of pressure on strongly correlated electron system plays an important role to discuss the quantum criticality and to study the detailed properties of the system. In this work, temperature dependence of the electrical resistivity of YbNi${}_4$P${}_2$ was measured under high pressure to understand the basics of competing nature among 4f valence of Yb ion, long range magnetic order and Kondo effect.