Major Rat Infestation

I have seen rats around before, but feel my run is secure. I’ve been putting the feed away again every night the last few nights since I saw a rat scurry across the top of the run about a week ago.Well my first ever tomato garden just started ripening (I planted it late, but live in CA, so we have a long season) and the rats started eating them. So tonight I went out with a headlamp to sprinkle natural rat repellant and saw several rats, one of which was trying to get into the chicken coop. I don’t think killing the rats will do any good (too many and they’ll just come back); I’d rather deter them. Can someone advise me on hot wire? Is there a good article here somewhere?
Also, tonight is the first night my six week old chicks are outside. They are in one of those little prefab coops inside the run. They’re too little to put in with the big girls yet. I’m wondering if I should bring them inside. Even though I have a hardware cloth skirt, rats can burrow under it and have in the past. The little coop seems secure, but it’s just a thin sliding door. Thoughts?