Doping-induced quantum crossover in Er2Ti2−xSnxO7

We present the results of the investigation of magnetic properties of the Er 2 Ti 2 − x Sn x O 7 series. For small doping values, the ordering temperature decreases linearly with x , while the moment configuration remains the same as in the x = 0 parent compound. Around x = 1.7 doping level, we observe a change in the behavior, where the ordering temperature starts to increase and new magnetic Bragg peaks appear. For the first time, we present evidence of a long-range order (LRO) in Er 2 Sn 2 O 7 ( x = 2.0 ) below T N = 130 mK. It is revealed that the moment configuration corresponds to a Palmer-Chalker type with a value of the magnetic moment significantly renormalized compared to x = 0 . We discuss our results in the framework of a possible quantum phase transition occurring close to x = 1.7 .