Metamagnetic transitions and anomalous magnetoresistance in EuAg 4 As 2 crystals

In this work, we systematically studied the magnetic and transport properties of EuAg4As2 single crystals. It was found that the two antiferromagnetic transitions (TN1 = 10 K and TN2=15 K) were driven to lower temperatures by an applied magnetic field. Below TN1, two successive metamagnetic transitions were observed when a magnetic field was applied in the ab plane (H//ab-plane). For both H//ab and H//c, EuAg4As2 showed a positive, unexpectedly large magnetoresistance (up to 202%) in lower magnetic fields below TN1, and a large negative magnetoresistance (up to −78%) at high fields/intermediate temperatures, thus presenting potential applications in magnetic sensors. Finally, the magnetic phase diagrams of EuAg4As2 were constructed for both H//ab and H//c using the resistivity and magnetisation data.