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The partial substitution of Mn for Ru in the bilayer ruthenate Sr₃(Ru_1-xMn_x)₂O₇ stabilizes long-range antiferromagnetic (AFM) ordering with the highest transition temperature T_N= 82 K for x = 0.16 [1]. Here, we report the observation of a well-defined symmetric zero-bias anomaly (ZBA) at 5.2 K in the scanning tunneling spectroscopy (STS) of x = 0.16. The temperature dependence of the ZBA shows thermal broadening and does not correlate with the bulk AFM transition. Consistent with this observation, there is no change in the ZBA with the application of a magnetic field (9T). This is in contrast to the case for x = 0, in which the ZBA is asymmetric about zero bias and magnetic field dependent which gradually vanished at 11T [2]. The more symmetric and narrower ZBA in x = 0.16 could originate from the distinct surface properties [3]. We will discuss the relationship between doping (disorder), the surface properties, and ZBA.


[1] B. Hu, G. T. McCandless, M. Menard, V. B. Nascimento, J. Y. Chan, E. W. Plummer, and R. Jin, Physical Review B 81, 184104 (2010).
[2] K. Iwaya et al., Physical Review Letters 99, 057208 (2007).
[3] C. Chen et al., Physical Review B 94, 085420 (2016).